51
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Schmid G, Schnorr K, Augustin S, Meister S, Lindenblatt H, Trost F, Liu Y, Braune M, Treusch R, Schröter CD, Pfeifer T, Moshammer R. Reaction microscope endstation at FLASH2. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:854-867. [PMID: 31074450 DOI: 10.1107/s1600577519002236] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 02/11/2019] [Indexed: 06/09/2023]
Abstract
A reaction microscope dedicated to multi-particle coincidence spectroscopy on gas-phase samples is installed at beamline FL26 of the free-electron laser FLASH2 in Hamburg. The main goals of the instrument are to follow the dynamics of atoms, molecules and small clusters on their natural time-scale and to study non-linear light-matter interaction with such systems. To this end, the reaction microscope is combined with an in-line extreme-ultraviolet (XUV) split-delay and focusing optics, which allows time-resolved XUV-XUV pump-probe spectroscopy to be performed.
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52
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Schmid G, Schnorr K, Augustin S, Meister S, Lindenblatt H, Trost F, Liu Y, Stojanovic N, Al-Shemmary A, Golz T, Treusch R, Gensch M, Kübel M, Foucar L, Rudenko A, Ullrich J, Schröter CD, Pfeifer T, Moshammer R. Terahertz-Field-Induced Time Shifts in Atomic Photoemission. PHYSICAL REVIEW LETTERS 2019; 122:073001. [PMID: 30848607 DOI: 10.1103/physrevlett.122.073001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Indexed: 06/09/2023]
Abstract
Time delays for atomic photoemission obtained in streaking or reconstruction of attosecond bursts by interference of two-photon transitions experiments originate from a combination of the quantum mechanical Wigner time and the Coulomb-laser coupling. While the former was investigated intensively theoretically as well as experimentally, the latter attracted less interest in experiments and has mostly been subject to calculations. Here, we present a measurement of the Coulomb-laser coupling-induced time shifts in photoionization of neon at 59.4 eV using a terahertz (THz) streaking field (λ=152 μm). Employing a reaction microscope at the THz beamline of the free-electron laser in Hamburg (FLASH), we have measured relative time shifts of up to 70 fs between the emission of 2p photoelectrons (∼38 eV) and low-energetic (<1 eV) photoelectrons. A comparison with theoretical predictions on Coulomb-laser coupling reveals reasonably good agreement.
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53
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Shcherbinin M, Westergaard FV, Hanif M, Krishnan SR, LaForge AC, Richter R, Pfeifer T, Mudrich M. Inelastic scattering of photoelectrons from He nanodroplets. J Chem Phys 2019; 150:044304. [PMID: 30709284 DOI: 10.1063/1.5074130] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
We present a detailed study of inelastic energy-loss collisions of photoelectrons emitted from He nanodroplets by tunable extreme ultraviolet (XUV) radiation. Using coincidence imaging detection of electrons and ions, we probe the lowest He droplet excited states up to the electron impact ionization threshold. We find significant signal contributions from photoelectrons emitted from free He atoms accompanying the He nanodroplet beam. Furthermore, signal contributions from photoionization and electron impact excitation/ionization occurring in pairs of nearest-neighbor atoms in the He droplets are detected. This work highlights the importance of inelastic electron scattering in the interaction of nanoparticles with XUV radiation.
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54
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Stooß V, Cavaletto SM, Donsa S, Blättermann A, Birk P, Keitel CH, Březinová I, Burgdörfer J, Ott C, Pfeifer T. Real-Time Reconstruction of the Strong-Field-Driven Dipole Response. PHYSICAL REVIEW LETTERS 2018; 121:173005. [PMID: 30411962 DOI: 10.1103/physrevlett.121.173005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Indexed: 06/08/2023]
Abstract
The reconstruction of the full temporal dipole response of a strongly driven time-dependent system from a single absorption spectrum is demonstrated, only requiring that a sufficiently short pulse is employed to initialize the coherent excitation of the system. We apply this finding to the time-domain observation of Rabi cycling between doubly excited atomic states in the few-femtosecond regime. This allows us to pinpoint the breakdown of few-level quantum dynamics at the critical laser intensity near 2 TW/cm^{2} in doubly excited helium. The present approach unlocks single-shot real-time-resolved signal reconstruction across timescales down to attoseconds for nonequilibrium states of matter. In contrast to conventional pump-probe schemes, there is no need for scanning time delays in order to access real-time information. The potential future applications of this technique range from testing fundamental quantum dynamics in strong fields to measuring and controlling ultrafast chemical and biological reaction processes when applied to traditional transient-absorption spectroscopy.
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55
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Micke P, Kühn S, Buchauer L, Harries JR, Bücking TM, Blaum K, Cieluch A, Egl A, Hollain D, Kraemer S, Pfeifer T, Schmidt PO, Schüssler RX, Schweiger C, Stöhlker T, Sturm S, Wolf RN, Bernitt S, Crespo López-Urrutia JR. The Heidelberg compact electron beam ion traps. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:063109. [PMID: 29960545 DOI: 10.1063/1.5026961] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Electron beam ion traps (EBITs) are ideal tools for both production and study of highly charged ions (HCIs). In order to reduce their construction, maintenance, and operation costs, we have developed a novel, compact, room-temperature design, the Heidelberg Compact EBIT (HC-EBIT). Four already commissioned devices operate at the strongest fields (up to 0.86 T) reported for such EBITs using permanent magnets, run electron beam currents up to 80 mA, and energies up to 10 keV. They demonstrate HCI production, trapping, and extraction of pulsed Ar16+ bunches and continuous 100 pA ion beams of highly charged Xe up to charge state 29+, already with a 4 mA, 2 keV electron beam. Moreover, HC-EBITs offer large solid-angle ports and thus high photon count rates, e.g., in x-ray spectroscopy of dielectronic recombination in HCIs up to Fe24+, achieving an electron-energy resolving power of E/ΔE > 1500 at 5 keV. Besides traditional on-axis electron guns, we have also implemented a novel off-axis gun for laser, synchrotron, and free-electron laser applications, offering clear optical access along the trap axis. We report on its first operation at a synchrotron radiation facility demonstrating the resonant photoexcitation of highly charged oxygen.
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56
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Blessenohl MA, Dobrodey S, Warnecke C, Rosner MK, Graham L, Paul S, Baumann TM, Hockenbery Z, Hubele R, Pfeifer T, Ames F, Dilling J, Crespo López-Urrutia JR. An electron beam ion trap and source for re-acceleration of rare-isotope ion beams at TRIUMF. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:052401. [PMID: 29864823 DOI: 10.1063/1.5021045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Electron beam driven ionization can produce highly charged ions (HCIs) in a few well-defined charge states. Ideal conditions for this are maximally focused electron beams and an extremely clean vacuum environment. A cryogenic electron beam ion trap fulfills these prerequisites and delivers very pure HCI beams. The Canadian rare isotope facility with electron beam ion source-electron beam ion sources developed at the Max-Planck-Institut für Kernphysik (MPIK) reaches already for a 5 keV electron beam and a current of 1 A with a density in excess of 5000 A/cm2 by means of a 6 T axial magnetic field. Within the trap, the beam quickly generates a dense HCI population, tightly confined by a space-charge potential of the order of 1 keV times the ionic charge state. Emitting HCI bunches of ≈107 ions at up to 100 Hz repetition rate, the device will charge-breed rare-isotope beams with the mass-over-charge ratio required for re-acceleration at the Advanced Rare IsotopE Laboratory (ARIEL) facility at TRIUMF. We present here its design and results from commissioning runs at MPIK, including X-ray diagnostics of the electron beam and charge-breeding process, as well as ion injection and HCI-extraction measurements.
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57
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Bezençon O, Remeň L, Richard S, Roch C, Kessler M, Moon R, Mawet J, Ertel EA, Pfeifer T, Capeleto B. Discovery and evaluation of Ca v 3.1-selective T-type calcium channel blockers. Bioorg Med Chem Lett 2017; 27:5322-5325. [DOI: 10.1016/j.bmcl.2017.09.063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 09/27/2017] [Accepted: 09/29/2017] [Indexed: 11/30/2022]
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58
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Bezençon O, Remeň L, Richard S, Roch C, Kessler M, Ertel EA, Moon R, Mawet J, Pfeifer T, Capeleto B. Discovery and evaluation of Ca v 3.2-selective T-type calcium channel blockers. Bioorg Med Chem Lett 2017; 27:5326-5331. [DOI: 10.1016/j.bmcl.2017.09.062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 09/27/2017] [Accepted: 09/29/2017] [Indexed: 10/18/2022]
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59
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Bezençon O, Heidmann B, Siegrist R, Stamm S, Richard S, Pozzi D, Corminboeuf O, Roch C, Kessler M, Ertel EA, Reymond I, Pfeifer T, de Kanter R, Toeroek-Schafroth M, Moccia LG, Mawet J, Moon R, Rey M, Capeleto B, Fournier E. Discovery of a Potent, Selective T-type Calcium Channel Blocker as a Drug Candidate for the Treatment of Generalized Epilepsies. J Med Chem 2017; 60:9769-9789. [PMID: 29116786 DOI: 10.1021/acs.jmedchem.7b01236] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We report here the discovery and pharmacological characterization of N-(1-benzyl-1H-pyrazol-3-yl)-2-phenylacetamide derivatives as potent, selective, brain-penetrating T-type calcium channel blockers. Optimization focused mainly on solubility, brain penetration, and the search for an aminopyrazole metabolite that would be negative in an Ames test. This resulted in the preparation and complete characterization of compound 66b (ACT-709478), which has been selected as a clinical candidate.
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60
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Bezençon O, Siegrist R, Heidmann B, Pozzi D, Stamm S, Remeň L, Richard S, Simons L, Gaston R, Downing D, Grisostomi C, Roch C, Kessler M, Gatfield J, Moon R, Pfeifer T, Mosbacher J, Reymond I, Ertel EA, de Kanter R, Capeleto B, Fournier E, Rey M, Moccia L, Toeroek-Schafroth M, Roscher R, Schindelholz B. Milestones to the Discovery of T-type Calcium Channel Blockers for the Treatment of Generalized Epilepsies. Chimia (Aarau) 2017; 71:722-729. [PMID: 29070417 DOI: 10.2533/chimia.2017.722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We describe the discovery and optimization of new, brain-penetrant T-type calcium channel blockers. We present optimized compounds with excellent efficacy in a rodent model of generalized absence-like epilepsy. Along the fine optimization of a chemical series with a pharmacological target located in the CNS (target potency, brain penetration, and solubility), we successfully identified an Ames negative aminopyrazole as putative metabolite of this compound series. Our efforts culminated in the selection of compound 20, which was elected as a preclinical candidate.
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61
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Gnerre C, Segrestaa J, Seeland S, Äänismaa P, Pfeifer T, Delahaye S, de Kanter R, Ichikawa T, Yamada T, Treiber A. The metabolism and drug-drug interaction potential of the selective prostacyclin receptor agonist selexipag. Xenobiotica 2017; 48:704-719. [PMID: 28737453 DOI: 10.1080/00498254.2017.1357088] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
1. The metabolism of selexipag has been studied in vivo in man and the main excreted metabolites were identified. Also, metabolites circulating in human plasma have been structurally identified and quantified. 2. The main metabolic pathway of selexipag in man is the formation of the active metabolite ACT-333679. Other metabolic pathways include oxidation and dealkylation reactions. All primary metabolites undergo subsequent hydrolysis of the sulphonamide moiety to their corresponding acids. ACT-333679 undergoes conjugation with glucuronic acid and aromatic hydroxylation to P10, the main metabolite detected in human faeces. 3. The formation of the active metabolite ACT-333679 is catalysed by carboxylesterases, while the oxidation and dealkylation reactions are metabolized by CYP2C8 and CYP3A4. CYP2C8 is the only P450 isoform catalysing the aromatic hydroxylation to P10. CYP2C8 together with CYP3A4 are also involved in the formation of several minor ACT-333679 metabolites. UGT1A3 and UGT2B7 catalyse the glucuronidation of ACT-333679. 4. The potential of selexipag to inhibit or induce cytochrome P450 enzymes or drug transport proteins was studied in vitro. Selexipag is an inhibitor of CYP2C8 and CYP2C9 and induces CYP3A4 and CYP2C9 in vitro. Also, selexipag inhibits the transporters OATP1B1, OATP1B3, OAT1, OAT3, and BCRP. However, due to its low dose and relatively low unbound exposure, selexipag has a low potential for causing drug-drug interactions.
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62
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Heeg KP, Kaldun A, Strohm C, Reiser P, Ott C, Subramanian R, Lentrodt D, Haber J, Wille HC, Goerttler S, Rüffer R, Keitel CH, Röhlsberger R, Pfeifer T, Evers J. Spectral narrowing of x-ray pulses for precision spectroscopy with nuclear resonances. Science 2017; 357:375-378. [PMID: 28751603 DOI: 10.1126/science.aan3512] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/26/2017] [Indexed: 11/02/2022]
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63
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Camus N, Yakaboylu E, Fechner L, Klaiber M, Laux M, Mi Y, Hatsagortsyan KZ, Pfeifer T, Keitel CH, Moshammer R. Experimental Evidence for Quantum Tunneling Time. PHYSICAL REVIEW LETTERS 2017; 119:023201. [PMID: 28753333 DOI: 10.1103/physrevlett.119.023201] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Indexed: 06/07/2023]
Abstract
The first hundred attoseconds of the electron dynamics during strong field tunneling ionization are investigated. We quantify theoretically how the electron's classical trajectories in the continuum emerge from the tunneling process and test the results with those achieved in parallel from attoclock measurements. An especially high sensitivity on the tunneling barrier is accomplished here by comparing the momentum distributions of two atomic species of slightly deviating atomic potentials (argon and krypton) being ionized under absolutely identical conditions with near-infrared laser pulses (1300 nm). The agreement between experiment and theory provides clear evidence for a nonzero tunneling time delay and a nonvanishing longitudinal momentum of the electron at the "tunnel exit."
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64
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Kaldun A, Blättermann A, Stooß V, Donsa S, Wei H, Pazourek R, Nagele S, Ott C, Lin CD, Burgdörfer J, Pfeifer T. Observing the ultrafast buildup of a Fano resonance in the time domain. Science 2017; 354:738-741. [PMID: 27846603 DOI: 10.1126/science.aah6972] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 09/30/2016] [Indexed: 11/02/2022]
Abstract
Although the time-dependent buildup of asymmetric Fano line shapes in absorption spectra has been of great theoretical interest in the past decade, experimental verification of the predictions has been elusive. Here, we report the experimental observation of the emergence of a Fano resonance in the prototype system of helium by interrupting the autoionization process of a correlated two-electron excited state with a strong laser field. The tunable temporal gate between excitation and termination of the resonance allows us to follow the formation of a Fano line shape in time. The agreement with ab initio calculations validates our experimental time-gating technique for addressing an even broader range of topics, such as the emergence of electron correlation, the onset of electron-internuclear coupling, and quasi-particle formation.
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65
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Mi Y, Camus N, Fechner L, Laux M, Moshammer R, Pfeifer T. Electron-Nuclear Coupling through Autoionizing States after Strong-Field Excitation of H_{2} Molecules. PHYSICAL REVIEW LETTERS 2017; 118:183201. [PMID: 28524692 DOI: 10.1103/physrevlett.118.183201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Indexed: 06/07/2023]
Abstract
Channel-selective electron emission from strong-field photoionization of H_{2} molecules is experimentally investigated by using ultrashort laser pulses and a reaction microscope. The electron momenta and energy spectra in coincidence with bound and dissociative ionization channels are compared. Surprisingly, we observed an enhancement of the photoelectron yield in the low-energy region for the bound ionization channel. By further investigation of asymmetrical electron emission using two-color laser pulses, this enhancement is understood as the population of the autoionizing states of H_{2} molecules in which vibrational energy is transferred to electronic energy. This general mechanism provides access to the vibrational-state distribution of molecular ions produced in a strong-field interaction.
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66
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Panchaud P, Bruyère T, Blumstein AC, Bur D, Chambovey A, Ertel EA, Gude M, Hubschwerlen C, Jacob L, Kimmerlin T, Pfeifer T, Prade L, Seiler P, Ritz D, Rueedi G. Discovery and Optimization of Isoquinoline Ethyl Ureas as Antibacterial Agents. J Med Chem 2017; 60:3755-3775. [DOI: 10.1021/acs.jmedchem.6b01834] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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67
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Wolter B, Pullen MG, Le AT, Baudisch M, Doblhoff-Dier K, Senftleben A, Hemmer M, Schröter CD, Ullrich J, Pfeifer T, Moshammer R, Gräfe S, Vendrell O, Lin CD, Biegert J. Ultrafast electron diffraction imaging of bond breaking in di-ionized acetylene. Science 2017; 354:308-312. [PMID: 27846561 DOI: 10.1126/science.aah3429] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/19/2016] [Indexed: 01/27/2023]
Abstract
Visualizing chemical reactions as they occur requires atomic spatial and femtosecond temporal resolution. Here, we report imaging of the molecular structure of acetylene (C2H2) 9 femtoseconds after ionization. Using mid-infrared laser-induced electron diffraction (LIED), we obtained snapshots as a proton departs the [C2H2]2+ ion. By introducing an additional laser field, we also demonstrate control over the ultrafast dissociation process and resolve different bond dynamics for molecules oriented parallel versus perpendicular to the LIED field. These measurements are in excellent agreement with a quantum chemical description of field-dressed molecular dynamics.
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68
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Mizuno T, Cörlin P, Miteva T, Gokhberg K, Kuleff A, Cederbaum LS, Pfeifer T, Fischer A, Moshammer R. Time-resolved observation of interatomic excitation-energy transfer in argon dimers. J Chem Phys 2017; 146:104305. [PMID: 28298097 DOI: 10.1063/1.4978233] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The ultrafast transfer of excitation energy from one atom to its neighbor is observed in singly charged argon dimers in a time-resolved extreme ultraviolet (XUV)-pump IR-probe experiment. In the pump step, bound 3s-hole states in the dimer are populated by single XUV-photon ionization. The excitation-energy transfer at avoided crossings of the potential-energy curves leads to dissociation of the dimer, which is experimentally observed by further ionization with a time-delayed IR-probe pulse. From the measured pump-probe delay-dependent kinetic-energy release of coincident Ar+ + Ar+ ions, we conclude that the transfer of energy occurs on a time scale of about 800fs. This mechanism represents a fast relaxation process below the energy threshold for interatomic Coulombic decay.
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69
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Siegrist R, Pozzi D, Jacob G, Torrisi C, Colas K, Braibant B, Mawet J, Pfeifer T, de Kanter R, Roch C, Kessler M, Moon R, Corminboeuf O, Bezençon O. Correction to Structure–Activity Relationship, Drug Metabolism and Pharmacokinetics Properties Optimization, and in Vivo Studies of New Brain Penetrant Triple T-Type Calcium Channel Blockers. J Med Chem 2017; 60:2163. [DOI: 10.1021/acs.jmedchem.7b00219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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70
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Liu Z, Wang Q, Ding J, Cavaletto SM, Pfeifer T, Hu B. Observation and quantification of the quantum dynamics of a strong-field excited multi-level system. Sci Rep 2017; 7:39993. [PMID: 28051167 PMCID: PMC5209658 DOI: 10.1038/srep39993] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 11/30/2016] [Indexed: 11/29/2022] Open
Abstract
The quantum dynamics of a V-type three-level system, whose two resonances are first excited by a weak probe pulse and subsequently modified by another strong one, is studied. The quantum dynamics of the multi-level system is closely related to the absorption spectrum of the transmitted probe pulse and its modification manifests itself as a modulation of the absorption line shape. Applying the dipole-control model, the modulation induced by the second strong pulse to the system’s dynamics is quantified by eight intensity-dependent parameters, describing the self and inter-state contributions. The present study opens the route to control the quantum dynamics of multi-level systems and to quantify the quantum-control process.
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71
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Meyer K, Müller N, Liu Z, Pfeifer T. Temporal resolution beyond the average pulse duration in shaped noisy-pulse transient absorption spectroscopy. APPLIED OPTICS 2016; 55:10318-10322. [PMID: 28059252 DOI: 10.1364/ao.55.010318] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In time-resolved spectroscopy, it is a widespread belief that the temporal resolution is determined by the laser pulse duration. Recently, it was observed and shown that partially coherent laser pulses as they are provided by free-electron-laser (FEL) sources offer an alternative route to reach a temporal resolution below the average pulse duration. Here, we demonstrate the generation of partially coherent light in the laboratory like we observe it at FELs. We present the successful implementation of such statistically fluctuating pulses by using the pulse-shaping technique. These pulses exhibit an average pulse duration about 10 times larger than their bandwidth limit. The shaped pulses are then applied to transient-absorption measurements in the dye IR144. Despite the noisy characteristics of the laser pulses, features in the measured absorption spectra occurring on time scales much faster than the average pulse duration are resolved, thus proving the universality of the described noisy-pulse concept.
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72
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Siegrist R, Pozzi D, Jacob G, Torrisi C, Colas K, Braibant B, Mawet J, Pfeifer T, de Kanter R, Roch C, Kessler M, Corminboeuf O, Bezençon O. Structure–Activity Relationship, Drug Metabolism and Pharmacokinetics Properties Optimization, and in Vivo Studies of New Brain Penetrant Triple T-Type Calcium Channel Blockers. J Med Chem 2016; 59:10661-10675. [DOI: 10.1021/acs.jmedchem.6b01356] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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73
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Remen L, Bezençon O, Simons L, Gaston R, Downing D, Gatfield J, Roch C, Kessler M, Mosbacher J, Pfeifer T, Grisostomi C, Rey M, Ertel EA, Moon R. Preparation, Antiepileptic Activity, and Cardiovascular Safety of Dihydropyrazoles as Brain-Penetrant T-Type Calcium Channel Blockers. J Med Chem 2016; 59:8398-411. [DOI: 10.1021/acs.jmedchem.6b00756] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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74
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LaForge AC, Stumpf V, Gokhberg K, von Vangerow J, Stienkemeier F, Kryzhevoi NV, O'Keeffe P, Ciavardini A, Krishnan SR, Coreno M, Prince KC, Richter R, Moshammer R, Pfeifer T, Cederbaum LS, Mudrich M. Enhanced Ionization of Embedded Clusters by Electron-Transfer-Mediated Decay in Helium Nanodroplets. PHYSICAL REVIEW LETTERS 2016; 116:203001. [PMID: 27258866 DOI: 10.1103/physrevlett.116.203001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Indexed: 06/05/2023]
Abstract
We report the observation of electron-transfer-mediated decay (ETMD) involving magnesium (Mg) clusters embedded in helium (He) nanodroplets. ETMD is initiated by the ionization of He followed by removal of two electrons from the Mg clusters of which one is transferred to the He ion while the other electron is emitted into the continuum. The process is shown to be the dominant ionization mechanism for embedded clusters for photon energies above the ionization potential of He. For Mg clusters larger than five atoms we observe stable doubly ionized clusters. Thus, ETMD provides an efficient pathway to the formation of doubly ionized cold species in doped nanodroplets.
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75
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Ding T, Ott C, Kaldun A, Blättermann A, Meyer K, Stooss V, Rebholz M, Birk P, Hartmann M, Brown A, Van Der Hart H, Pfeifer T. Time-resolved four-wave-mixing spectroscopy for inner-valence transitions. OPTICS LETTERS 2016; 41:709-12. [PMID: 26872169 DOI: 10.1364/ol.41.000709] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Noncollinear four-wave-mixing (FWM) techniques at near-infrared (NIR), visible, and ultraviolet frequencies have been widely used to map vibrational and electronic couplings, typically in complex molecules. However, correlations between spatially localized inner-valence transitions among different sites of a molecule in the extreme ultraviolet (XUV) spectral range have not been observed yet. As an experimental step toward this goal, we perform time-resolved FWM spectroscopy with femtosecond NIR and attosecond XUV pulses. The first two pulses (XUV-NIR) coincide in time and act as coherent excitation fields, while the third pulse (NIR) acts as a probe. As a first application, we show how coupling dynamics between odd- and even-parity, inner-valence excited states of neon can be revealed using a two-dimensional spectral representation. Experimentally obtained results are found to be in good agreement with ab initio time-dependent R-matrix calculations providing the full description of multielectron interactions, as well as few-level model simulations. Future applications of this method also include site-specific probing of electronic processes in molecules.
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