1
|
Nag P, Ranković M, Polášek M, Čurík R, Slaughter DS, Fedor J. Contrasting Dynamics in Isoelectronic Anions Formed by Electron Attachment. J Phys Chem Lett 2024; 15:895-902. [PMID: 38241169 PMCID: PMC10839900 DOI: 10.1021/acs.jpclett.3c03460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 01/09/2024] [Accepted: 01/12/2024] [Indexed: 01/21/2024]
Abstract
Cyanogen NCCN and cyanoacetylene HCCCN are isoelectronic molecules, and as such, they have many similar properties. We focus on the bond cleavage in these induced by the dissociative electron attachment. In both molecules, resonant electron attachment produces CN- with very similar energy dependence. We investigate the very different dissociation dynamics, in each of the two molecules, revealed by velocity map imaging of this common fragment. Different dynamics are manifested both in the excess energy partitioning and in the angular distributions of fragments. Based on the comparison with electron energy loss spectra, which provide information about possible parent states of the resonances (both optically allowed and forbidden excited states of the neutral target), we ascribe the observed effect to the distortion of the nuclear frame during the formation of core-excited resonance in cyanoacetylene. The proposed mechanism also explains a puzzling difference in the magnitude of the CN- cross section in the two molecules which has been so far unexplained.
Collapse
Affiliation(s)
- P. Nag
- J.
Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech
Republic
| | - M. Ranković
- J.
Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech
Republic
| | - M. Polášek
- J.
Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech
Republic
| | - R. Čurík
- J.
Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech
Republic
| | - D. S. Slaughter
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - J. Fedor
- J.
Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech
Republic
| |
Collapse
|
2
|
Ragesh Kumar TP, Nag P, Ranković M, Luxford TFM, Kočišek J, Mašín Z, Fedor J. Distant Symmetry Control in Electron-Induced Bond Cleavage. J Phys Chem Lett 2022; 13:11136-11142. [PMID: 36441975 DOI: 10.1021/acs.jpclett.2c03096] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We experimentally show that N-H bond cleavage in the pyrrole molecule following resonant electron attachment is allowed and controlled by the motion of the atoms which are not dissociating, namely, of the carbon-attached hydrogen atoms. We use this fact to steer the efficiency of this bond cleavage. In order to interpret the experimental findings, we have developed a method for locating all resonant and virtual states of an electron-molecule system in the complex plane, based on all-electron R-matrix scattering calculations. Mapping these as a function of molecular geometry allows us to separate two contributing dissociation mechanisms: a π* resonance formation inducing strong bending deformations and a nonresonant σ* mechanism originating in a virtual state. The coupling between the two mechanisms is enabled by the out-of-plane motion of the C-H bonds, and we show that it must happen on an ultrafast (few fs) time scale.
Collapse
Affiliation(s)
- T P Ragesh Kumar
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223Prague, Czech Republic
| | - P Nag
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223Prague, Czech Republic
| | - M Ranković
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223Prague, Czech Republic
| | - T F M Luxford
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223Prague, Czech Republic
| | - J Kočišek
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223Prague, Czech Republic
| | - Z Mašín
- Faculty of Mathematics and Physics, Charles University, Institute of Theoretical Physics, V Holešovičkách 2, 18000Prague, Czech Republic
| | - J Fedor
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223Prague, Czech Republic
| |
Collapse
|
3
|
Asfandiarov NL, Muftakhov MV, Pshenichnyuk SA, Rakhmeev RG, Safronov AM, Markova AV, Vorob'ev AS, Luxford TFM, Kočišek J, Fedor J. Non-covalent anion structures in dissociative electron attachment to some brominated biphenyls. J Chem Phys 2021; 155:244302. [PMID: 34972364 DOI: 10.1063/5.0074013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The present work combines experiment and theory to reveal the behavior of bromo-substituted-biphenyls after an electron attachment. We experimentally determine anion lifetimes using an electron attachment-magnetic sector mass spectrometer instrument. Branching ratios of dissociative electron attachment fragments on longer timescales are determined using the electron attachment-quadrupole mass spectrometer instrument. In all cases, fragmentation is low: Only the Br- and [M-Br]- ions are detected, and [M-H]- is observed only in the case of 4-Br-biphenyl and parent anion lifetimes as long as 165 µs are observed. Such lifetimes are contradictory to the dissociation rates of 2- and 4-bromobiphenyl, as measured by the pulse radiolysis method to be 3.2 × 1010 and >5 × 1010 s-1, respectively. The discrepancy is plausibly explained by our calculation of the potential energy surface of the dissociating anion. Isolated in vacuum, the bromide anion can orbit the polarized aromatic radical at a long distance. A series of local minima on the potential energy surface allows for a roaming mechanism prolonging the detection time of such weakly bound complex anions. The present results illuminate the behavior recently observed in a series of bromo-substituted compounds of biological as well as technological relevance.
Collapse
Affiliation(s)
- N L Asfandiarov
- Institute of Molecule and Crystal Physics - Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
| | - M V Muftakhov
- Institute of Molecule and Crystal Physics - Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
| | - S A Pshenichnyuk
- Institute of Molecule and Crystal Physics - Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
| | - R G Rakhmeev
- Institute of Molecule and Crystal Physics - Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
| | - A M Safronov
- Institute of Molecule and Crystal Physics - Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
| | - A V Markova
- Institute of Molecule and Crystal Physics - Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
| | - A S Vorob'ev
- Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, 141700 Dolgoprudny, Moscow Region, Russia
| | - T F M Luxford
- Department of Dynamics of Molecules and Clusters, J. Heyrovský Institute of Physical Chemistry of Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - J Kočišek
- Department of Dynamics of Molecules and Clusters, J. Heyrovský Institute of Physical Chemistry of Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - J Fedor
- Department of Dynamics of Molecules and Clusters, J. Heyrovský Institute of Physical Chemistry of Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| |
Collapse
|
4
|
Luxford TFM, Fedor J, Kočišek J. Electron attachment to tetrazoles: The influence of molecular structure on ring opening reactivity. J Chem Phys 2021; 154:214303. [PMID: 34240967 DOI: 10.1063/5.0052011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The electron-induced reactivity of 5-(4-chlorophenyl)-1H-tetrazole and 5-chloro-1-phenyl-1H-tetrazole was studied using a trochoidal electron monochromator quadrupole mass spectrometer experimental setup. 5-(4-chlorophenyl)-1H-tetrazole underwent dissociative electron attachment to form Cl-, [M-HCl]-, and [M-H]-. 5-chloro-1-phenyl-1H-tetrazole underwent associative electron attachment to form the parent anion and dissociative electron attachment to form Cl-, CN2Cl-, [M-N2-Cl]-, and [M-HCl]-. For each anion product, the ion yield was measured as a function of incident electron energy. Density functional theory calculations were performed to support the experimental results with estimates of the energetic thresholds for the different reaction pathways. While the tetrazole group is susceptible to electron-induced ring opening in both molecules, this process was only observed for 5-chloro-1-phenyl-1H-tetrazole, indicating that this process is influenced by the structure of the molecule.
Collapse
Affiliation(s)
- T F M Luxford
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| | - J Fedor
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| | - J Kočišek
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| |
Collapse
|
5
|
Abstract
We probe the transient anion states (resonances) in the dielectric gas C4F7N by the electron energy loss spectroscopy and the dissociative electron attachment spectroscopy. The vibrationally inelastic electron scattering leads to two excitation types. The first is the excitation of specific vibrational modes that are assigned with the help of an infrared spectrum of this molecule and quantum chemistry calculations. In the second type of vibrational excitation, the excess energy is randomized via internal vibrational redistribution in the temporary anion, and the electrons are emitted statistically. The electron attachment proceeds in three different regimes. The first is the formation of the parent C4F7N- anion at energies close to 0 eV. The second is a statistical evaporation of the F-atom, leading to the defluorinated anion C4F6N-. Finally, the third is dissociative electron attachment proceeding via the formation of several resonances and leading to a number of fragments. The present data explain the puzzling recent results of the pulsed-Townsend experiments with this gas.
Collapse
Affiliation(s)
- M Ranković
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - Ragesh Kumar T P
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - P Nag
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - J Kočišek
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - J Fedor
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| |
Collapse
|
6
|
Fedor J. Comment on "Dipole-Supported Electronic Resonances Mediate Electron-Induced Amide Bond Cleavage". Phys Rev Lett 2020; 124:199301. [PMID: 32469549 DOI: 10.1103/physrevlett.124.199301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Affiliation(s)
- J Fedor
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| |
Collapse
|
7
|
Med J, Sršeň Š, Slavíček P, Domaracka A, Indrajith S, Rousseau P, Fárník M, Fedor J, Kočišek J. Vibrationally Mediated Stabilization of Electrons in Nonpolar Matter. J Phys Chem Lett 2020; 11:2482-2489. [PMID: 32154726 DOI: 10.1021/acs.jpclett.0c00278] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We explore solvation of electrons in nonpolar matter, here represented by butadiene clusters. Isolated butadiene supports only the existence of transient anions (resonances). Two-dimensional electron energy loss spectroscopy shows that the resonances lead to an efficient vibrational excitation of butadiene, which can result into the almost complete loss of energy of the interacting electron. Cluster-beam experiments show that molecular clusters of butadiene form stable anions, however only at sizes of more than 9 molecular units. We have calculated the distribution of electron affinities of clusters using classical and path integral molecular dynamics simulations. There is almost a continuous transition from the resonant to the bound anions with an increase in cluster size. The comparison of the classical and quantum dynamics reveals that the electron binding is strongly supported by molecular vibrations, brought about by nuclear zero-point motion and thermal agitation. We also inspected the structure of the solvated electron, finding it well localized.
Collapse
Affiliation(s)
- Jakub Med
- Department of Physical Chemistry, University of Chemistry and Technology, Technická 5, 16628 Prague 6, Czech Republic
| | - Štěpán Sršeň
- Department of Physical Chemistry, University of Chemistry and Technology, Technická 5, 16628 Prague 6, Czech Republic
| | - Petr Slavíček
- Department of Physical Chemistry, University of Chemistry and Technology, Technická 5, 16628 Prague 6, Czech Republic
- J. Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - A Domaracka
- Normandie Univ., ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, 14000 Caen, France
| | - S Indrajith
- Normandie Univ., ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, 14000 Caen, France
| | - P Rousseau
- Normandie Univ., ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, 14000 Caen, France
| | - M Fárník
- J. Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - J Fedor
- J. Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - J Kočišek
- J. Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| |
Collapse
|
8
|
Kumar T P R, Kočišek J, Bravaya K, Fedor J. Electron-induced vibrational excitation and dissociative electron attachment in methyl formate. Phys Chem Chem Phys 2020; 22:518-524. [PMID: 31829379 DOI: 10.1039/c9cp05165a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We probe the low-energy electron collisions with methyl formate HCOOCH3, focusing on its resonant states. Experimentally, we (i) use two-dimensional electron energy loss spectroscopy to gain information about the vibrational excitation and (ii) report the absolute dissociative electron attachment cross sections. The electron scattering spectra reveal both the threshold effects due to the long-range electron-molecule interaction and a pronounced π* resonance centered around 2.1 eV. This resonance gives rise to dissociative electron attachment into three different anionic channels, the strongest one being the production of the formate anion. Theoretically, we characterize this resonant state using the complex absorbing potential approach combined with multistate multireference perturbation theory, which predicts its position and width in excellent agreement with the experiment.
Collapse
Affiliation(s)
- Ragesh Kumar T P
- J. Heyrovský Institute of Physical Chemistry v.v.i., Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic.
| | | | | | | |
Collapse
|
9
|
Asfandiarov NL, Pshenichnyuk SA, Rakhmeyev RG, Tuktarov RF, Zaitsev NL, Vorob’ev AS, Kočišek J, Fedor J, Modelli A. 4-Bromobiphenyl: Long-lived molecular anion formation and competition between electron detachment and dissociation. J Chem Phys 2019; 150:114304. [DOI: 10.1063/1.5082611] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- N. L. Asfandiarov
- Institute of Molecule and Crystal Physics UFRC RAS, October Avenue 151, 450075 Ufa, Russia
| | - S. A. Pshenichnyuk
- Institute of Molecule and Crystal Physics UFRC RAS, October Avenue 151, 450075 Ufa, Russia
| | - R. G. Rakhmeyev
- Institute of Molecule and Crystal Physics UFRC RAS, October Avenue 151, 450075 Ufa, Russia
| | - R. F. Tuktarov
- Institute of Molecule and Crystal Physics UFRC RAS, October Avenue 151, 450075 Ufa, Russia
| | - N. L. Zaitsev
- Institute of Molecule and Crystal Physics UFRC RAS, October Avenue 151, 450075 Ufa, Russia
| | - A. S. Vorob’ev
- Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, 141700 Dolgoprudny, Moscow Region, Russia
| | - J. Kočišek
- Department of Dynamics of Molecules and Clusters, J. Heyrovský Institute of Physical Chemistry Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - J. Fedor
- Department of Dynamics of Molecules and Clusters, J. Heyrovský Institute of Physical Chemistry Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - A. Modelli
- Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
- Centro Interdipartimentale di Ricerca in Scienze Ambientali, Università di Bologna, via S. Alberto 163, 48100 Ravenna, Italy
| |
Collapse
|
10
|
Ranković M, Chalabala J, Zawadzki M, Kočišek J, Slavíček P, Fedor J. Dissociative ionization dynamics of dielectric gas C3F7CN. Phys Chem Chem Phys 2019; 21:16451-16458. [PMID: 31312828 DOI: 10.1039/c9cp02188d] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fluoronitrile C3F7CN is a promising candidate for the replacement of SF6 dielectric gas in high-voltage insulation.
Collapse
Affiliation(s)
- M. Ranković
- J. Heyrovský Institute of Physical Chemistry
- Czech Academy of Sciences
- 18223 Prague
- Czech Republic
| | - J. Chalabala
- Department of Physical Chemistry
- University of Chemistry and Technology
- 16628 Prague
- Czech Republic
| | - M. Zawadzki
- J. Heyrovský Institute of Physical Chemistry
- Czech Academy of Sciences
- 18223 Prague
- Czech Republic
- Department of Atomic, Molecular, and Optical Physics
| | - J. Kočišek
- J. Heyrovský Institute of Physical Chemistry
- Czech Academy of Sciences
- 18223 Prague
- Czech Republic
| | - P. Slavíček
- J. Heyrovský Institute of Physical Chemistry
- Czech Academy of Sciences
- 18223 Prague
- Czech Republic
- Department of Physical Chemistry
| | - J. Fedor
- J. Heyrovský Institute of Physical Chemistry
- Czech Academy of Sciences
- 18223 Prague
- Czech Republic
| |
Collapse
|
11
|
Abstract
We probe the electron attachment in hexafluoropropylene oxide (HFPO), C3F6O, a gas widely used in plasma technologies. We determine the absolute electron attachment cross section using two completely different experimental approaches: (i) a crossed-beam experiment at single collision conditions (local pressures of 5 × 10-4 mbar) and (ii) a pulsed Townsend experiment at pressures of 20-100 mbar. In the latter method, the cross sections are unfolded from the electron attachment rate coefficients. The cross sections derived independently by the two methods are in very good agreement. We additionally discuss the dissociative electron attachment fragmentation patterns and their role in the radical production in industrial HFPO plasmas.
Collapse
Affiliation(s)
- M Zawadzki
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - A Chachereau
- Power Systems and High Voltage Laboratories, ETH Zurich, Physikstr. 3, 8092 Zurich, Switzerland
| | - J Kočišek
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - C M Franck
- Power Systems and High Voltage Laboratories, ETH Zurich, Physikstr. 3, 8092 Zurich, Switzerland
| | - J Fedor
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| |
Collapse
|
12
|
Zawadzki M, Čížek M, Houfek K, Čurík R, Ferus M, Civiš S, Kočišek J, Fedor J. Resonances and Dissociative Electron Attachment in HNCO. Phys Rev Lett 2018; 121:143402. [PMID: 30339415 DOI: 10.1103/physrevlett.121.143402] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Indexed: 06/08/2023]
Abstract
In a combined experimental and theoretical study, we probe the dissociative electron attachment in isocyanic acid HNCO. The experimental absolute cross section for the NCO^{-} fragment shows a sharp onset and fine structures near the threshold. The autoionizing state responsible for the dissociative attachment is found in both the R-matrix calculation and using analytic continuation in the coupling constant. The involved A^{'} resonance has a mixed π^{*}/σ^{*} character along the dissociating bond and thus combines the effects of nonzero electron angular momentum and dipole-supported states. This leads to unusual behavior of its width at various geometries. Because the potential energy gradient of the autoionizing state points essentially in the direction of the N─H bond, nuclear dynamics can be described by a one-dimensional nonlocal model. The results agree with the experiment both quantitatively and qualitatively. The present system may be a prototype for interpretation of the dissociative electron attachment process in a number of other polyatomic systems.
Collapse
Affiliation(s)
- M Zawadzki
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
- Department of Atomic, Molecular and Optical Physics, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, ul. G. Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - M Čížek
- Faculty of Mathematics and Physics, Charles University, Institute of Theoretical Physics, V Holešovičkách 2, 18000 Prague, Czech Republic
| | - K Houfek
- Faculty of Mathematics and Physics, Charles University, Institute of Theoretical Physics, V Holešovičkách 2, 18000 Prague, Czech Republic
| | - R Čurík
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - M Ferus
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - S Civiš
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - J Kočišek
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - J Fedor
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| |
Collapse
|
13
|
Zawadzki M, Ranković M, Kočišek J, Fedor J. Dissociative electron attachment and anion-induced dimerization in pyruvic acid. Phys Chem Chem Phys 2018; 20:6838-6844. [PMID: 29350234 DOI: 10.1039/c7cp07472g] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report partial cross sections for the dissociative electron attachment to pyruvic acid. A rich fragmentation dynamics is observed. Electronic structure calculations facilitate the identification of complex rearrangement reactions that occur during the dissociation. Furthermore, a number of fragment anions produced at electron energies close to 0 eV are observed, that cannot originate from single electron-molecule collisions. We ascribe their production to secondary reactions of the transient anions with neutral molecules. Such reactions turn out to be unusually efficient; the most probable reason for this is that they proceed via the formation of a double-hydrogen-bonded complex followed by an ultrafast proton transfer between the reaction partners.
Collapse
Affiliation(s)
- M Zawadzki
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic.
| | | | | | | |
Collapse
|
14
|
Affiliation(s)
- J. Kočišek
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - R. Janečková
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland
| | - J. Fedor
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| |
Collapse
|
15
|
Allan M, Lacko M, Papp P, Matejčík Š, Zlatar M, Fabrikant II, Kočišek J, Fedor J. Dissociative electron attachment and electronic excitation in Fe(CO)5. Phys Chem Chem Phys 2018; 20:11692-11701. [DOI: 10.1039/c8cp01387j] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In a combined experimental and theoretical study we characterize dissociative electron attachment (DEA) to, and electronically excited states of, Fe(CO)5.
Collapse
Affiliation(s)
- M. Allan
- Department of Chemistry
- University of Fribourg
- 1700 Fribourg
- Switzerland
| | - M. Lacko
- Department of Experimental Physics
- Comenius University
- 84215 Bratislava
- Slovakia
| | - P. Papp
- Department of Experimental Physics
- Comenius University
- 84215 Bratislava
- Slovakia
| | - Š. Matejčík
- Department of Experimental Physics
- Comenius University
- 84215 Bratislava
- Slovakia
| | - M. Zlatar
- Department of Chemistry
- Institute of Chemistry
- Technology and Metallurgy (IChTM)
- University of Belgrade
- 11001 Belgrade
| | - I. I. Fabrikant
- Department of Physics and Astronomy
- University of Nebraska
- Lincoln
- USA
| | - J. Kočišek
- J. Heyrovský Institute of Physical Chemistry v.v.i
- Czech Academy of Sciences
- 18223 Prague 8
- Czech Republic
| | - J. Fedor
- J. Heyrovský Institute of Physical Chemistry v.v.i
- Czech Academy of Sciences
- 18223 Prague 8
- Czech Republic
| |
Collapse
|
16
|
Poštulka J, Slavíček P, Fedor J, Fárník M, Kočišek J. Energy Transfer in Microhydrated Uracil, 5-Fluorouracil, and 5-Bromouracil. J Phys Chem B 2017; 121:8965-8974. [DOI: 10.1021/acs.jpcb.7b07390] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. Poštulka
- Department
of Physical Chemistry, University of Chemistry and Technology, Technická
5, Prague 6, Czech Republic
| | - P. Slavíček
- Department
of Physical Chemistry, University of Chemistry and Technology, Technická
5, Prague 6, Czech Republic
- J.
Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - J. Fedor
- J.
Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - M. Fárník
- J.
Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - J. Kočišek
- J.
Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| |
Collapse
|
17
|
Abstract
When ionizing radiation passes biological matter, a large number of secondary electrons with very low energies (<3 eV) is produced. It is known that such electrons cause an efficient fragmentation of isolated nucleobases via dissociative electron attachment. We present an experimental study of the electron attachment to microhydrated nucleobases. Our novel approach allows significant control over the hydration of molecules studied in the molecular beam. We directly show for the first time that the presence of a few water molecules suppresses the dissociative channel and leads exclusively to formation of intact molecular and hydrated anions. The suppression of fragmentation is ascribed to caging-like effects and fast energy transfer to the solvent. This is in contrast with theoretical prediction that microhydration strongly enhances the fragmentation of nucleobases. The current observation impacts mechanisms of reductive DNA strand breaks proposed to date on the basis of gas-phase experiments.
Collapse
Affiliation(s)
- J Kočišek
- J. Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences , Dolejškova 3, 18223 Prague, Czech Republic
| | - A Pysanenko
- J. Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences , Dolejškova 3, 18223 Prague, Czech Republic
| | - M Fárník
- J. Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences , Dolejškova 3, 18223 Prague, Czech Republic
| | - J Fedor
- J. Heyrovský Institute of Physical Chemistry v.v.i., The Czech Academy of Sciences , Dolejškova 3, 18223 Prague, Czech Republic
| |
Collapse
|
18
|
Iavarone M, Moore SA, Fedor J, Ciocys ST, Karapetrov G, Pearson J, Novosad V, Bader SD. Visualizing domain wall and reverse domain superconductivity. Nat Commun 2014; 5:4766. [PMID: 25164004 PMCID: PMC4354251 DOI: 10.1038/ncomms5766] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 07/22/2014] [Indexed: 11/12/2022] Open
Abstract
In magnetically coupled, planar ferromagnet-superconductor (F/S) hybrid structures, magnetic domain walls can be used to spatially confine the superconductivity. In contrast to a superconductor in a uniform applied magnetic field, the nucleation of the superconducting order parameter in F/S structures is governed by the inhomogeneous magnetic field distribution. The interplay between the superconductivity localized at the domain walls and far from the walls leads to effects such as re-entrant superconductivity and reverse domain superconductivity with the critical temperature depending upon the location. Here we use scanning tunnelling spectroscopy to directly image the nucleation of superconductivity at the domain wall in F/S structures realized with Co-Pd multilayers and Pb thin films. Our results demonstrate that such F/S structures are attractive model systems that offer the possibility to control the strength and the location of the superconducting nucleus by applying an external magnetic field, potentially useful to guide vortices for computing application. When superconductivity emerges in a thin superconductor grown on a ferromagnet, it does so in an array of interacting superconducting and normally conducting channels. Maria Iavarone and colleagues use scanning tunnelling microscopy to image how these channels form and interact.
Collapse
Affiliation(s)
- M Iavarone
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - S A Moore
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - J Fedor
- 1] Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA [2]
| | - S T Ciocys
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - G Karapetrov
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - J Pearson
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - V Novosad
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - S D Bader
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| |
Collapse
|
19
|
Lengyel J, Pysanenko A, Poterya V, Slavíček P, Fárník M, Kočišek J, Fedor J. Irregular shapes of water clusters generated in supersonic expansions. Phys Rev Lett 2014; 112:113401. [PMID: 24702366 DOI: 10.1103/physrevlett.112.113401] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Indexed: 05/26/2023]
Abstract
We report cross sections for pickup of guest molecules on neutral argon and water clusters with the mean sizes in the range from N = 50 to 600. The experiments are supported by molecular dynamics simulations and analytical models based on the interaction potentials. The cross sections for argon clusters are consistent with their assumed spherical shape and follow approximately the theoretically justified N(1/3) dependence. On the other hand, the cross sections of water clusters depart from this dependence and are considerably larger starting from N ≥ 300. We interpret this increase of cross section by the occurrence of highly irregular shapes of water clusters produced in the supersonic expansion of water vapor under the conditions of the large cluster generation.
Collapse
Affiliation(s)
- J Lengyel
- J. Heyrovský Institute of Physical Chemistry v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague, Czech Republic
| | - A Pysanenko
- J. Heyrovský Institute of Physical Chemistry v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague, Czech Republic
| | - V Poterya
- J. Heyrovský Institute of Physical Chemistry v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague, Czech Republic
| | - P Slavíček
- J. Heyrovský Institute of Physical Chemistry v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague, Czech Republic
| | - M Fárník
- J. Heyrovský Institute of Physical Chemistry v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague, Czech Republic
| | - J Kočišek
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland
| | - J Fedor
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland
| |
Collapse
|
20
|
Janečková R, Kubala D, May O, Fedor J, Allan M. Experimental evidence on the mechanism of dissociative electron attachment to formic acid. Phys Rev Lett 2013; 111:213201. [PMID: 24313485 DOI: 10.1103/physrevlett.111.213201] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Indexed: 06/02/2023]
Abstract
Two mechanisms for dissociative electron attachment in HCOOH, the formation of HCOO(-)+H, were proposed in the literature: (i) via a direct electron attachment into a σ* resonance, augmented by dipole binding of the incident electron [G. A. Gallup et al., Phys. Rev. A 79, 042701 (2009)], and (ii) with the 1.8 eV π* resonance as a doorway state, linked to the products by symmetry lowering-distortion of the temporary anion, primarily the C-H bond, from the planar symmetry [T. N. Rescigno et al., Phys. Rev. Lett. 96, 213201 (2006)]. The later mechanism implies a reduction of the cross section upon deuteration of the hydrogen bonded to the C atom, whereas the former mechanism would leave the cross section unaffected. Our experimental absolute cross sections for the four isotopomers of formic acid show that deuteration on the C atom reduces the cross section value only marginally (by 12%) compared to deuteration on the O atom (reduction by a factor of 16), and thus favor mechanism (i).
Collapse
Affiliation(s)
- R Janečková
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, 1700 Fribourg, Switzerland
| | | | | | | | | |
Collapse
|
21
|
Affiliation(s)
- D. Kubala
- Département de Chimie, Université de Fribourg , Fribourg, Switzerland
| | - K. Regeta
- Département de Chimie, Université de Fribourg , Fribourg, Switzerland
| | - R. Janečková
- Département de Chimie, Université de Fribourg , Fribourg, Switzerland
| | - J. Fedor
- Département de Chimie, Université de Fribourg , Fribourg, Switzerland
| | - S. Grimme
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie der Universität Bonn , Bonn, Germany
| | - A. Hansen
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie der Universität Bonn , Bonn, Germany
| | | | - M. Allan
- Département de Chimie, Université de Fribourg , Fribourg, Switzerland
| |
Collapse
|
22
|
Johansson JO, Fedor J, Goto M, Kjellberg M, Stenfalk J, Henderson GG, Campbell EEB, Hansen K. Anisotropic hot electron emission from fullerenes. J Chem Phys 2012; 136:164301. [PMID: 22559476 DOI: 10.1063/1.4704828] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Photoelectron spectra for fullerenes C(60) and C(70) ionized using 800 nm laser pulses with pulse durations from 120 to 1000 fs show thermal electron kinetic energy distributions but they also exhibit angular anisotropy with respect to the laser light polarization. The effective temperature of electrons, measured along the laser polarization direction, is significantly higher than in the perpendicular direction. We explain this observation by considering that the emission of the thermal electrons is uncorrelated with the phase of the laser pulse, unlike directly ionized electrons, and, depending on the time of emission, they may experience an additional "kick" from the vector potential of the laser field when they are emitted from the molecule.
Collapse
Affiliation(s)
- J O Johansson
- EaStCHEM, School of Chemistry, University of Edinburgh, Edinburgh EH9 3JJ, Scotland
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Lengyel J, Kočišek J, Poterya V, Pysanenko A, Svrčková P, Fárník M, Zaouris DK, Fedor J. Uptake of atmospheric molecules by ice nanoparticles: Pickup cross sections. J Chem Phys 2012; 137:034304. [DOI: 10.1063/1.4733987] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
24
|
Fedor J, Poterya V, Pysanenko A, Fárník M. Cluster cross sections from pickup measurements: Are the established methods consistent? J Chem Phys 2011; 135:104305. [PMID: 21932891 DOI: 10.1063/1.3633474] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- J Fedor
- J. Heyrovský Institute of Physical Chemistry v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague, Czech Republic.
| | | | | | | |
Collapse
|
25
|
Fedor J, Kočišek J, Poterya V, Votava O, Pysanenko A, Lipciuc ML, Kitsopoulos TN, Fárník M. Velocity map imaging of HBr photodissociation in large rare gas clusters. J Chem Phys 2011; 134:154303. [DOI: 10.1063/1.3578610] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
26
|
Cambel V, Eliás P, Gregusová D, Fedor J, Martaus J, Karapetrov G, Novosad V, Kostic I. Novel magnetic tips developed for the switching magnetization magnetic force microscopy. J Nanosci Nanotechnol 2010; 10:4477-4481. [PMID: 21128443 DOI: 10.1166/jnn.2010.2366] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Using micromagnetic calculations we search for optimal magnetic properties of novel magnetic tips to be used for a Switching Magnetization Magnetic Force Microscopy (SM-MFM), a novel technique based on two-pass scanning with reversed tip magnetization. Within the technique the sum of two scans images local atomic forces and their difference maps the local magnetic forces. The tip magnetization is switched during the scanning by a small magnetic field. The technology of novel low-coercitive magnetic tips is proposed. For best performance the tips must exhibit low magnetic moment, low switching field, and single-domain state at remanence. Such tips are equipped with Permalloy objects of a precise shape that are defined on their tilted sides. We calculate switching fields of such tips by solving the micromagnetic problem to find the optimum shape and dimensions of the Permalloy objects located on the tips. Among them, hexagon was found as the best shape for the tips.
Collapse
Affiliation(s)
- V Cambel
- Institute of Electrical Engineering, Slovak Academy of Sciences, Dubravska cesta 9, 84104 Bratislava, Slovakia
| | | | | | | | | | | | | | | |
Collapse
|
27
|
Iavarone M, Karapetrov G, Fedor J, Rosenmann D, Nishizaki T, Kobayashi N. The local effect of magnetic impurities on superconductivity in CoxNbSe2 and MnxNbSe2 single crystals. J Phys Condens Matter 2010; 22:015501. [PMID: 21386227 DOI: 10.1088/0953-8984/22/1/015501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We investigate the effect of individual atomic impurities on the superconducting state that they are embedded in. Using low temperature scanning tunneling microscopy and spectroscopy we could identify Co and Mn atoms in the Co(x)NbSe(2) and Mn(x)NbSe(2) single crystals and observe the influence on the local electronic density of states (LDOS) at 0.4 K. We find that Co is in the weak scattering limit. In this case the LDOS is quite homogeneous on the sample surface, despite the number of defects, and retains sharp coherent superconducting peaks. This is in strong contrast to the effects of Mn impurities, which locally destroy superconductivity. In this case the LDOS shows a strong enhancement of spectral weight inside the superconducting gap even far from the Mn atoms. Moreover, two impurity bound states are found within the superconducting gap at E/Δ(0) = 0.18 and 0.36 at locations close to defects.
Collapse
Affiliation(s)
- M Iavarone
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA.
| | | | | | | | | | | |
Collapse
|
28
|
Graupner K, Haughey SA, Field TA, Mayhew CA, Hoffmann TH, May O, Fedor J, Allan M, Fabrikant II, Illenberger E, Braun M, Ruf MW, Hotop H. Low-Energy Electron Attachment to the Dichlorodifluoromethane (CCl2F2) Molecule. J Phys Chem A 2009; 114:1474-84. [DOI: 10.1021/jp9081992] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- K. Graupner
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - S. A. Haughey
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - T. A. Field
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - C. A. Mayhew
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - T. H. Hoffmann
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - O. May
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - J. Fedor
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - M. Allan
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - I. I. Fabrikant
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - E. Illenberger
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - M. Braun
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - M.-W. Ruf
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - H. Hotop
- Department of Physics and Astronomy, Queen’s University, Belfast BT7 1NN, U.K., School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K., Département de Chimie, Université de Fribourg, CH-1700 Fribourg, Switzerland, Fachbereich Physik, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany, Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, and Physikalische und Theoretische Chemie, Freie Universität Berlin, 14195 Berlin, Germany
| |
Collapse
|
29
|
Gregušová D, Martaus J, Fedor J, Kúdela R, Kostič I, Cambel V. On-tip sub-micrometer Hall probes for magnetic microscopy prepared by AFM lithography. Ultramicroscopy 2009; 109:1080-4. [DOI: 10.1016/j.ultramic.2009.03.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
30
|
Fedor J, Echt O, Głuch K, Matt-Leubner S, Scheier P, Märk T. On the role of the II(1/2g) state in spontaneous dissociation of krypton and xenon dimer ions. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.02.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
31
|
Fedor J, Głuch K, Parajuli R, Matt-Leubner S, Echt O, Scheier P, Märk TD. Mechanisms and dynamics of the metastable decay in Ar2+. J Chem Phys 2006; 121:7253-8. [PMID: 15473793 DOI: 10.1063/1.1794011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A detailed experimental as well as theoretical investigation of the properties of the metastable dissociation Ar2+ --> Ar+ + Ar is presented. The mass-analyzed ion kinetic energy (MIKE) scan technique has been performed using a three sector field mass spectrometer. The possible mechanisms of the metastability of Ar2+ have been examined and the observed decay process is assigned to the II(1/2)(u)-->I(1/2)(g) bound to continuum radiative transition, in agreement with earlier work. The calculation of the theoretical shape of the kinetic energy release distribution of fragment ions allowed us to construct the theoretical MIKE peak and compare it with the raw experimental data. The accuracy of various sets of potential energy curves for Ar2+ is discussed, as well as the way of production of the metastable Ar2+[II(1/2)(u)] electronic state by electron impact. Excellent agreement between the experimental data and theoretical model has been observed.
Collapse
Affiliation(s)
- J Fedor
- Institut für Ionenphysik, Leopold-Franzens Universität, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | | | | | | | | | | | | |
Collapse
|
32
|
Karapetrov G, Fedor J, Iavarone M, Rosenmann D, Kwok WK. Direct observation of geometrical phase transitions in mesoscopic superconductors by scanning tunneling microscopy. Phys Rev Lett 2005; 95:167002. [PMID: 16241833 DOI: 10.1103/physrevlett.95.167002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Indexed: 05/05/2023]
Abstract
Using scanning tunneling microscopy, we mapped the distribution of the local density of states in a single crystal superconductor heterostructure with an array of submicron normal metal islands. We observe the coexistence of strongly interacting multiquanta vortex lattice with interstitial Abrikosov vortices. The newly formed composite magnetic flux structure undergoes a series of phase transitions between different topological configuration states. The vortex configuration states are strongly dependent on the number of flux quanta and the nanoscale confinement architecture of the mesoscopic superconductor. Here, we present images of vortex phase transitions due to confinement effects when the number of magnetic flux quanta in the system changes. The vortex dynamics in these systems could serve as a model for behavior of confined many-body systems when the number of particles changes.
Collapse
Affiliation(s)
- G Karapetrov
- Materials Science Division, Argonne National Laboratory, Illinois 60439, USA
| | | | | | | | | |
Collapse
|
33
|
Compton S, Balaban K, Wilkoff B, Fedor J, Wright C, MacMillan S, Zhang X. 399 Initial experience of the remote ICD monitoring system-housecall plus. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/eupace/7.supplement_1.86-a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- S. Compton
- Alaska Heart Institute, Anchorage, AL, United States of America
| | - K. Balaban
- Alaska Heart Institute, Anchorage, AL, United States of America
| | - B.L. Wilkoff
- Cleveland Clinic Foundation, Cleveland, OH, United States of America
| | - J. Fedor
- Sanger Clinic, Charlotte, NC, United States of America
| | - C. Wright
- St. Jude Medical, Sylmar, United States of America
| | - S. MacMillan
- St. Jude Medical, Sylmar, United States of America
| | - X. Zhang
- Valencia, United States of America
| |
Collapse
|
34
|
Abstract
The metastable decay of dimer anions of Cu and Ag has been measured in a storage ring. The decay is found to proceed nonexponentially and is well described by a power law with an exponent of -1. This signals the presence of a continuum of decay constants in the ensemble. This quasicontinuum can be provided by the quantum mechanical tunneling decay of high angular momentum states populated in the source. Numerical calculations for dimers of a variety of elements suggest that this decay behavior can be expected for a wide range of species.
Collapse
Affiliation(s)
- J Fedor
- Institute for Ion Physics, Technikerstrasse 25, Leopold-Franzens Universität, A-6020 Innsbruck, Austria
| | | | | | | |
Collapse
|
35
|
Fedor J, Parajuli R, Matt-Leubner S, Echt O, Hagelberg F, Głuch K, Stamatovic A, Probst M, Scheier P, Märk TD. Probing electronic states of Ne2+ and Ar2+ by measuring kinetic-energy-release distributions. Phys Rev Lett 2003; 91:133401. [PMID: 14525302 DOI: 10.1103/physrevlett.91.133401] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2003] [Indexed: 05/24/2023]
Abstract
Dissociative decay of metastable, electronically excited neon and argon dimer ions produces fragment ions with strikingly dissimilar kinetic-energy-release distributions. The distributions have been modeled based on ab initio calculations of potential energy curves. The unusual bimodal distribution observed for dissociation of Ne2+ arises from competition between radiative and nonradiative decay of the long-lived II(1/2)(u) state. For Ar2+, however, electronic predissociation is insignificant.
Collapse
Affiliation(s)
- J Fedor
- Institut für Ionenphysik, Leopold Franzens Universität, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Głuch K, Fedor J, Matt-Leubner S, Echt O, Stamatovic A, Probst M, Scheier P, Märk TD. Kinetic-energy release in Coulomb explosion of metastable C3H52+. J Chem Phys 2003. [DOI: 10.1063/1.1536978] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
37
|
Mair C, Herman Z, Fedor J, Lezius M, Märk TD. Surface-induced dissociations and reactions of acetonitrile monomer, dimer and trimer ions. J Chem Phys 2003. [DOI: 10.1063/1.1522398] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
|
38
|
Krowka J, Stites D, Debs R, Larsen C, Fedor J, Brunette E, Düzgünes N. Lymphocyte proliferative responses to soluble and liposome-conjugated envelope peptides of HIV-1. J Immunol 1990; 144:2535-40. [PMID: 1969450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The proliferation of lymphocytes from HIV-seronegative (HIV Ab-) and seropositive (HIV Ab+) individuals in response to two synthetic peptide epitopes of HIV envelope glycoproteins (ENVgp) was evaluated as an index of cell-mediated immunity in infected individuals. All HIV Ab- and most HIV Ab+ individuals' lymphocytes failed to proliferate in primary cultures in response to the two soluble HIV ENVgp peptides, ENVP346 and ENVP466 even in the presence of rIL-2. After stimulation with liposome-conjugates of ENVP346 or ENVP466 and soluble rIL-2, however, CD4 lymphocytes from some HIV Ab+ individuals were able to proliferate. Significantly higher frequencies of rIL-2-augmented proliferative responses to liposome-conjugated ENVP346 or ENVP466 were observed in HIV Ab+ asymptomatic individuals as compared to patients with AIDS-related conditions or AIDS. These studies indicate that the conjugation of HIV peptides or proteins to liposomes and stimulation with rIL-2 may enhance cell-mediated responses to these peptides.
Collapse
Affiliation(s)
- J Krowka
- Department of Laboratory Medicine, University of California, San Francisco 94143
| | | | | | | | | | | | | |
Collapse
|
39
|
Krowka J, Stites D, Debs R, Larsen C, Fedor J, Brunette E, Düzgünes N. Lymphocyte proliferative responses to soluble and liposome-conjugated envelope peptides of HIV-1. The Journal of Immunology 1990. [DOI: 10.4049/jimmunol.144.7.2535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The proliferation of lymphocytes from HIV-seronegative (HIV Ab-) and seropositive (HIV Ab+) individuals in response to two synthetic peptide epitopes of HIV envelope glycoproteins (ENVgp) was evaluated as an index of cell-mediated immunity in infected individuals. All HIV Ab- and most HIV Ab+ individuals' lymphocytes failed to proliferate in primary cultures in response to the two soluble HIV ENVgp peptides, ENVP346 and ENVP466 even in the presence of rIL-2. After stimulation with liposome-conjugates of ENVP346 or ENVP466 and soluble rIL-2, however, CD4 lymphocytes from some HIV Ab+ individuals were able to proliferate. Significantly higher frequencies of rIL-2-augmented proliferative responses to liposome-conjugated ENVP346 or ENVP466 were observed in HIV Ab+ asymptomatic individuals as compared to patients with AIDS-related conditions or AIDS. These studies indicate that the conjugation of HIV peptides or proteins to liposomes and stimulation with rIL-2 may enhance cell-mediated responses to these peptides.
Collapse
Affiliation(s)
- J Krowka
- Department of Laboratory Medicine, University of California, San Francisco 94143
| | - D Stites
- Department of Laboratory Medicine, University of California, San Francisco 94143
| | - R Debs
- Department of Laboratory Medicine, University of California, San Francisco 94143
| | - C Larsen
- Department of Laboratory Medicine, University of California, San Francisco 94143
| | - J Fedor
- Department of Laboratory Medicine, University of California, San Francisco 94143
| | - E Brunette
- Department of Laboratory Medicine, University of California, San Francisco 94143
| | - N Düzgünes
- Department of Laboratory Medicine, University of California, San Francisco 94143
| |
Collapse
|
40
|
Shavnin SA, Pedroso de Lima MC, Fedor J, Wood P, Bentz J, Düzgüneş N. Cholesterol affects divalent cation-induced fusion and isothermal phase transitions of phospholipid membranes. Biochim Biophys Acta 1988; 946:405-16. [PMID: 3207754 DOI: 10.1016/0005-2736(88)90416-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The influence of cholesterol on divalent cation-induced fusion and isothermal phase transitions of large unilamellar vesicles composed of phosphatidylserine (PS) was investigated. Vesicle fusion was monitored by the terbium/dipicolinic acid assay for the intermixing of internal aqueous contents, in the temperature range 10-40 degrees C. The fusogenic activity of the cations decreases in the sequence Ca2+ greater than Ba2+ greater than Sr2+ much greater than Mg2+ for cholesterol concentrations in the range 20-40 mol%, and at all temperatures. Increasing the cholesterol concentration decreases the initial rate of fusion in the presence of Ca2+ and Ba2+ at 25 degrees C, reaching about 50% of the rate for pure PS at a mole fraction of 0.4. From 10 to 25 degrees C, Mg2+ is ineffective in causing fusion at all cholesterol concentrations. However, at 30 degrees C, Mg2+-induced fusion is observed with vesicles containing cholesterol. At 40 degrees C, Mg2+ induces slow fusion of pure PS vesicles, which is enhanced by the presence of cholesterol. Increasing the temperature also causes a monotonic increase in the rate of fusion induced by Ca2+, Ba2+ and Sr2+. The enhancement of the effect of cholesterol at high temperatures suggests that changes in hydrogen bonding and interbilayer hydration forces may be involved in the modulation of fusion by cholesterol. The phase behavior of PS/cholesterol membranes in the presence of Na+ and divalent cations was studied by differential scanning calorimetry. The temperature of the gel-liquid crystalline transition (Tm) in Na+ is lowered as the cholesterol content is increased, and the endotherm is broadened. Addition of divalent cations shifts the Tm upward, with a sequence of effectiveness Ba2+ greater than Sr2+ greater than Mg2+. The Tm of these complexes decreases as the cholesterol content is increased. Although the transition is not detectable for cholesterol concentrations of 40 and 50 mol% in the presence of Na+, Sr2+ or Mg2+, the addition of Ba2+ reveals endotherms with Tm progressively lower than that observed at 30 mol%. Although the presence of cholesterol appears to induce an isothermal gel-liquid crystalline transition by decreasing the Tm, this change in membrane fluidity does not enhance the rate of fusion, but rather decreases it. The effect of cholesterol on the fusion of PS/phosphatidylethanolamine (PE) vesicles was investigated by utilizing a resonance energy transfer assay for lipid mixing. The initial rate of fusion of PS/PE and PS/PE/cholesterol vesicles is saturated at high Mg2+ concentrations. With Ca2+, saturation is not observed for cholesterol-containing vesicles.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- S A Shavnin
- Cancer Research Institute, School of Medicine, University of California, San Francisco 94143
| | | | | | | | | | | |
Collapse
|
41
|
Düzgüneş N, Newton C, Fisher K, Fedor J, Papahadjopoulos D. Monolayer coupling in phosphatidylserine bilayers: distinct phase transitions induced by magnesium interacting with one or both monolayers. Biochim Biophys Acta 1988; 944:391-8. [PMID: 3179295 DOI: 10.1016/0005-2736(88)90510-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have investigated the thermotropic behavior of phospatidylserine bilayers interacting with Mg2+ either on one side or both sides, using differential scanning calorimetry. Large unilamellar vesicles (LUV) of phosphatidylserine exposed to Mg2+ on the external side only displayed an upward shift of the gel-liquid transition temperature (Tm) of about 6-8 degrees C relative to the Tm of LUV in Na+. Mg2+ was shown not to enter the vesicle interior, by means of fluorescence measurements on encapsulated 8-hydroxyquinoline-5-sulfonate. Multilamellar vesicles prepared in the presence of Mg2+, or vesicles prepared by Mg2+-induced fusion of small unilamellar vesicles, had Tm values that were shifted upward by about 16-17 C degrees. When the latter preparation was treated with EDTA to produce vesicles with Mg2+ inside and Na+ outside, the Tm was found to be shifted again by only 6-8 degrees C. These observations indicate that the monolayer interacting with Na+ fluidizes the monolayer interacting with Mg2+, and that the latter tends to solidify the former. The two monolayers thus appear to be coupled, possibly by hydrocarbon chain interdigitation.
Collapse
Affiliation(s)
- N Düzgüneş
- Cancer Research Institute, University of California, San Francisco 94143-0128
| | | | | | | | | |
Collapse
|
42
|
Shiffer KA, Goerke J, Düzgüneş N, Fedor J, Shohet SB. Interaction of erythrocyte protein 4.1 with phospholipids. A monolayer and liposome study. Biochim Biophys Acta 1988; 937:269-80. [PMID: 3337803 DOI: 10.1016/0005-2736(88)90249-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We have studied the interaction of purified human erythrocyte protein 4.1 with phospholipid membranes by monitoring both the increase in surface pressure of monolayers at the air/water interface and the change in permeability in liposomes to fluorescent molecules, in the presence of protein 4.1. Protein 4.1 penetrated into monolayers of brain phosphatidylserine (PS) and egg phosphatidylcholine (PC), even above surface pressures of 30 mN/m. Protein 4.1 increased the permeability of negatively charged PS, but not PC, liposomes, measured as the increase in fluorescence when encapsulated 1-aminonaphthalene-3,6,8-trisulfonic acid (ANTS) and p-xylenebispyridinium bromide (DPX) or carboxyfluorescein were released into the medium. The interaction of protein 4.1 with PS large unilamellar vesicles (LUV) was increased as the pH and the ionic strength were lowered, and decreased as the Ca2+ or Mg2+ concentrations and ionic strength were raised. In order to study the relevance of these measurements to the erythrocyte, we prepared LUV of synthetic lipid mixtures characteristic of both the inner and the outer membrane leaflets. Protein 4.1 increased the permeability of inner, but not outer, leaflet LUV at both pH 6.0 and 7.4. These observations suggest that negatively charged phospholipid domains around the protein 4.1 high-affinity protein-binding site(s) may contribute to the anchoring of protein 4.1 to the cytoplasmic surface of the red cell membrane.
Collapse
Affiliation(s)
- K A Shiffer
- Cardiovascular Research Institute, University of California, San Francisco 94143
| | | | | | | | | |
Collapse
|
43
|
Abstract
The kinetics of lipid mixing during membrane aggregation and fusion was monitored by two assays employing resonance energy transfer between N-(7-nitro-2,1,3-benzoxadiazol-4-yl)phosphatidylethanolamine (NBD-PE) and N-(lissamine Rhodamine B sulfonyl)phosphatidylethanolamine (Rh-PE). For the "probe mixing" assay, NBD-PE and Rh-PE were incorporated into separate populations of phospholipid vesicles. For the "probe dilution" assay, both probes were incorporated into one population of vesicles, and the assay monitored the dilution of the molecules into the membrane of unlabeled vesicles. The former assay was found to be very sensitive to aggregation, even when the internal aqueous contents of the vesicles did not intermix. Examples of this case were large unilamellar vesicles (LUV) composed of phosphatidylserine (PS) in the presence of Mg2+ and small unilamellar vesicles (SUV) composed of phosphatidylserine in the presence of high concentrations of Na+. No lipid mixing was detected in these cases by the probe dilution assay. Under conditions where membrane fusion (defined as the intermixing of aqueous contents with concomitant membrane mixing) was observed, such as LUV (PS) in the presence of Ca2+, the rate of probe mixing was faster than that of probe dilution, which in turn was faster than the rate of contents mixing. Two assays monitoring the intermixing of aqueous contents were also compared. The Tb/dipicolinic acid assay reported slower fusion rates than the 1-aminonaphthalene-3,6,8-trisulfonic acid/N,N'-p-xylylene-bis(pyridinium bromide) assay for PS LUV undergoing fusion in the presence of Ca2+. These observations point to the importance of utilizing contents mixing assays in conjunction with lipid mixing assays to obtain the rates of membrane destabilization and fusion.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- N Düzgüneş
- Cancer Research Institute, University of California, San Francisco 94143-0128
| | | | | | | |
Collapse
|
44
|
Meers P, Ernst JD, Düzgünes N, Hong KL, Fedor J, Goldstein IM, Papahadjopoulos D. Synexin-like proteins from human polymorphonuclear leukocytes. Identification and characterization of granule-aggregating and membrane-fusing activities. J Biol Chem 1987; 262:7850-8. [PMID: 2953727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We have used Ca2+-dependent binding to a phospholipid vesicle affinity column to isolate a mixture of three synexin-like proteins from the cytosol of human polymorphonuclear leukocytes (PMN), with relative molecular weights of approximately 67,000, 47,000, and 28,000. Rabbit antibodies raised against bovine liver synexin recognized the 47,000 molecular weight PMN protein. These PMN proteins, like bovine liver synexin, promoted aggregation of isolated PMN specific granules in the presence of Ca2+ and increased the overall rate of Ca2+-induced fusion of liposomes composed of phosphatidate (PA)/phosphatidylethanolamine (PE) (1:3) and phosphatidylserine/PE (1:3), but decreased the rate of spermine-induced fusion of PA/PE (1:3) liposomes. Using fluorescent lipid probes, rapid fusion of PA/PE liposomes with PMN specific granules (50% maximum signal within a few minutes) was observed when 1 mM Ca2+ was added in the presence of both synexin and free arachidonic acid. Dilution of the aqueous contents of liposomes was also observed under the same conditions. The rate of fusion increased monotonically with Ca2+ and arachidonic acid concentrations, but synexin exhibited an optimum concentration. Lack of any one of the components precluded rapid fusion. These results suggest that PMN contain a protein similar to, or identical with, synexin that may be involved in calcium-dependent fusion of intracellular membranes.
Collapse
|
45
|
Meers P, Ernst JD, Düzgünes N, Hong KL, Fedor J, Goldstein IM, Papahadjopoulos D. Synexin-like proteins from human polymorphonuclear leukocytes. Identification and characterization of granule-aggregating and membrane-fusing activities. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47645-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
46
|
Fedor J, Matolay T. [Incidence of dental caries in primary schools]. Fogorv Sz 1973; 66:289-92. [PMID: 4148484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
|
47
|
Sampson EJ, Fedor J, Benkovic PA, Benkovic SJ. Intramolecular and divalent metal ion catalysis. The hydrolytic mechanism of O-phenyl N-(glycyl)phosphoramidate. J Org Chem 1973; 38:1301-6. [PMID: 4694233 DOI: 10.1021/jo00947a011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
48
|
Fedor J, Galambos L. [Dental care during for pregnant women]. Fogorv Sz 1972; 65:345-7. [PMID: 4507431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
49
|
Fedor J, Galambos L, Vavrouics M. [The tasks of dental health education]. Fogorv Sz 1971; 64:84-5. [PMID: 5282807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
|
50
|
Inovay J, Fedor J. [A case of successfully treated fibrosarcoma]. Fogorv Sz 1970; 63:73-7. [PMID: 5266530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
|