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Žitnik M, Mihelič A, Bučar K, Kavčič M, Rubensson JE, Svanquist M, Söderström J, Feifel R, Såthe C, Ovcharenko Y, Lyamayev V, Mazza T, Meyer M, Simon M, Journel L, Lüning J, Plekan O, Coreno M, Devetta M, Di Fraia M, Finetti P, Richter R, Grazioli C, Prince KC, Callegari C. High resolution multiphoton spectroscopy by a tunable free-electron-laser light. PHYSICAL REVIEW LETTERS 2014; 113:193201. [PMID: 25415905 DOI: 10.1103/physrevlett.113.193201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Indexed: 06/04/2023]
Abstract
Seeded free electron lasers theoretically have the intensity, tunability, and resolution required for multiphoton spectroscopy of atomic and molecular species. Using the seeded free electron laser FERMI and a novel detection scheme, we have revealed the two-photon excitation spectra of dipole-forbidden doubly excited states in helium. The spectral profiles of the lowest (-1,0)(+1) (1)S(e) and (0,1)(0) (1)D(e) resonances display energy shifts in the meV range that depend on the pulse intensity. The results are explained by an effective two-level model based on calculated Rabi frequencies and decay rates.
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Affiliation(s)
- M Žitnik
- Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia and Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
| | - A Mihelič
- Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - K Bučar
- Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - M Kavčič
- Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - J-E Rubensson
- Uppsala University, Department of Physics and Astronomy, P.O. Box 530, S-75121 Uppsala, Sweden
| | - M Svanquist
- Uppsala University, Department of Physics and Astronomy, P.O. Box 530, S-75121 Uppsala, Sweden
| | - J Söderström
- Uppsala University, Department of Physics and Astronomy, P.O. Box 530, S-75121 Uppsala, Sweden
| | - R Feifel
- Uppsala University, Department of Physics and Astronomy, P.O. Box 530, S-75121 Uppsala, Sweden and University of Gothenburg, Department of Physics, SE-412 96 Gothenburg, Sweden
| | - C Såthe
- MAX IV Laboratory, Lund University, P.O. Box 118, 22100 Lund, Sweden
| | - Y Ovcharenko
- Technische Universität Berlin, Institut für Optik und Atomare Physik, Eugene-Wigner-Building Hardenbergstrasse 36, D-10623 Berlin, Germany
| | - V Lyamayev
- Institute of Physics, University of Freiburg, Hermann-Herder Strasse 3a, D-79104 Freiburg, Germany
| | - T Mazza
- European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany
| | - M Meyer
- European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany
| | - M Simon
- Sorbonne Université, UPMC Univ Paris 06, UMR 7614, LCPMR, 75005 Paris, France and CNRS, UMR 7614, LCPMR, 75005 Paris, France
| | - L Journel
- Sorbonne Université, UPMC Univ Paris 06, UMR 7614, LCPMR, 75005 Paris, France and CNRS, UMR 7614, LCPMR, 75005 Paris, France
| | - J Lüning
- Sorbonne Université, UPMC Univ Paris 06, UMR 7614, LCPMR, 75005 Paris, France and CNRS, UMR 7614, LCPMR, 75005 Paris, France
| | - O Plekan
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163, 5, I-34149 Basovizza, Trieste, Italy
| | - M Coreno
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163, 5, I-34149 Basovizza, Trieste, Italy
| | - M Devetta
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163, 5, I-34149 Basovizza, Trieste, Italy
| | - M Di Fraia
- Department of Physics, University of Trieste, Via Valerio 2, I-34124 Trieste, Italy
| | - P Finetti
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163, 5, I-34149 Basovizza, Trieste, Italy
| | - R Richter
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163, 5, I-34149 Basovizza, Trieste, Italy
| | - C Grazioli
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163, 5, I-34149 Basovizza, Trieste, Italy
| | - K C Prince
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163, 5, I-34149 Basovizza, Trieste, Italy and eChemistry Laboratory, Faculty of Life and Social Sciences, Swinburne University of Technology, Hawthorn, Melbourne, Victoria 3122, Australia
| | - C Callegari
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163, 5, I-34149 Basovizza, Trieste, Italy
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2
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Kasthurirangan S, Saha JK, Agnihotri AN, Bhattacharyya S, Misra D, Kumar A, Mukherjee PK, Santos JP, Costa AM, Indelicato P, Mukherjee TK, Tribedi LC. Observation of 2p3d(1Po)→1s3d(1De) radiative transition in He-like Si, S, and Cl ions. PHYSICAL REVIEW LETTERS 2013; 111:243201. [PMID: 24483657 DOI: 10.1103/physrevlett.111.243201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Indexed: 06/03/2023]
Abstract
We present an experimental determination of the 2p3d(1Po)→1s3d(1De) x-ray line emitted from He-like Si, S, and Cl projectile ions, excited in collisions with thin carbon foils, using a high-resolution bent-crystal spectrometer. A good agreement between the observation and state-of-the-art relativistic calculations using the multiconfiguration Dirac-Fock formalism including the Breit interaction and QED effects implies the dominance of fluorescent decay over the autoionization process for the 2p3d(^{1}P^{o}) state of He-like heavy ions. This is the first observation of the fluorescence-active doubly excited states in He-like Si, S, and Cl ions.
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Affiliation(s)
- S Kasthurirangan
- Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India and Department of Physics, Institute of Chemical Technology, Mumbai 400019, India
| | - J K Saha
- Narula Institute of Technology, Agarpara, Kolkata 700109, India
| | - A N Agnihotri
- Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India
| | | | - D Misra
- Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India
| | - A Kumar
- Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - P K Mukherjee
- Ramakrishna Mission Vivekananda University, Howrah 711202, India
| | - J P Santos
- Centro de Física Atómica, Departamento de Física, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, P-2829-516 Caparica, Portugal
| | - A M Costa
- Centro de Física Atómica, Departamento de Física, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, P-2829-516 Caparica, Portugal
| | - P Indelicato
- Laboratoire Kastler Brossel, École Normale Supérieure, CNRS, Université P. et M. Curie-Paris 6, Case 74; 4, place Jussieu, 75252 Paris CEDEX 05, France
| | - T K Mukherjee
- Narula Institute of Technology, Agarpara, Kolkata 700109, India
| | - L C Tribedi
- Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India
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Alagia M, Coreno M, Farrokhpour H, Franceschi P, Mihelic A, Moise A, Omidyan R, Prince KC, Richter R, Söderström J, Stranges S, Tabrizchi M, Zitnik M. Excitation of 1S and 3S metastable helium atoms to doubly excited states. PHYSICAL REVIEW LETTERS 2009; 102:153001. [PMID: 19518627 DOI: 10.1103/physrevlett.102.153001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2008] [Indexed: 05/27/2023]
Abstract
We present spectra of triplet and singlet metastable helium atoms resonantly photoexcited to doubly excited states. The first members of three dipole-allowed ;{1,3}P;{o} series have been observed and their relative photoionization cross sections determined, both in the triplet (from 1s2s ;{3}S;{e}) and singlet (from 1s2s ;{1}S;{e}) manifolds. The intensity ratios are drastically different with respect to transitions from the ground state. When radiation damping is included the results for the singlets are in agreement with theory, while for triplets spin-orbit interaction must also be taken into account.
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Affiliation(s)
- M Alagia
- CNR-ISMN Sezione Roma, I-00185 Roma, Italy
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Ström M, Såthe C, Agåker M, Söderström J, Rubensson JE, Stranges S, Richter R, Alagia M, Gorczyca TW, Robicheaux F. Magnetic-field induced enhancement in the fluorescence yield spectrum of doubly excited states in helium. PHYSICAL REVIEW LETTERS 2006; 97:253002. [PMID: 17280347 DOI: 10.1103/physrevlett.97.253002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Indexed: 05/13/2023]
Abstract
An influence of static magnetic fields on the fluorescence yield spectrum of He in the vicinity of the N = 2 thresholds has been observed. The experimental results are in excellent agreement with predictions based on multichannel quantum defect theory, and it is demonstrated that the Rydberg electron l mixing due to the diamagnetic interaction is essential for the description of the observed fluorescence yield intensity enhancement.
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Affiliation(s)
- Magnus Ström
- Department of Physics, Uppsala University, Box 530, S-75121 Uppsala, Sweden
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5
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Prince KC, Coreno M, Richter R, de Simone M, Feyer V, Kivimäki A, Mihelic A, Zitnik M. Detection of the 1pe series of doubly excited helium states below N=2 via the stark effect. PHYSICAL REVIEW LETTERS 2006; 96:093001. [PMID: 16606259 DOI: 10.1103/physrevlett.96.093001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2005] [Indexed: 05/08/2023]
Abstract
The Stark effect on the doubly excited states of helium below the N=2 threshold has been studied by vacuum ultraviolet fluorescence yield spectroscopy. Two new series of states are observed at moderate fields (<10 kV/cm), and assigned to the previously unobserved even 1pe series, and a group of 1De series. The 1Se states are observed indirectly via their mixing with nearby 1 po states. The observations at moderate field contradict theoretical predictions that field strengths about an order of magnitude greater are necessary to observe the Stark effect on He doubly excited states at low quantum numbers.
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Affiliation(s)
- K C Prince
- Sincrotrone Trieste, in Area Science Park, I-34012 Basovizza, Italy.
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6
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Såthe C, Ström M, Agåker M, Söderström J, Rubensson JE, Richter R, Alagia M, Stranges S, Gorczyca TW, Robicheaux F. Double excitations of helium in weak static electric fields. PHYSICAL REVIEW LETTERS 2006; 96:043002. [PMID: 16486817 DOI: 10.1103/physrevlett.96.043002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Indexed: 05/06/2023]
Abstract
A dramatic electric field dependence has been observed in the fluorescence yield spectrum of the doubly excited states in helium, where a rich phenomenology is encountered below the threshold. Fluorescence yields of certain states can be tuned to zero, while other dipole-forbidden states are significantly enhanced, for fields much weaker than 1 kV/cm. Using an R-matrix multichannel quantum defect theory, spherical-to-parabolic frame transformation method, we are able to reproduce the main features of the observed spectrum, and we discuss the qualitative behavior in terms of weak electric field mixing.
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Affiliation(s)
- Conny Såthe
- Physics Department, Box 530, S-751 21 Uppsala, Sweden
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7
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Liu XJ, Zhu LF, Yuan ZS, Li WB, Cheng HD, Huang YP, Zhong ZP, Xu KZ, Li JM. Dynamical correlation in double excitations of helium studied by high-resolution and angular-resolved fast-electron energy-loss spectroscopy in absolute measurements. PHYSICAL REVIEW LETTERS 2003; 91:193203. [PMID: 14611580 DOI: 10.1103/physrevlett.91.193203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2003] [Indexed: 05/24/2023]
Abstract
The momentum transfer dependence of fundamental double excitation processes of helium is studied by absolute measurements using an angular resolved fast-electron energy loss spectrometer with high energy resolution. It elucidates the dynamical correlations, in terms of internal correlation quantum numbers, K, T, and A. The Fano profile parameters q, f(a), rho2, f, and S of doubly excited states (2)(1,0)+2 (1)S(e), (2)(1,0)+2 (1)D(e), and (2)(0,1)+2 (1)P(o) are reported as functions of momentum transfer K2. Qualitative analysis is given for the states of (2)(-1,0)+2 (1)S(e) and (2)(1,0)+2 (1)S(e).
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Affiliation(s)
- Xiao-jing Liu
- Laboratory of Bond-Selective Chemistry, Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230027, China.
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Lambourne JG, Penent F, Lablanquie P, Hall RI, Ahmad M, Zitnik M, Bucar K, Odling-Smee MK, Harries JR, Hammond P, Waterhouse DK, Stranges S, Richter R, Alagia M, Coreno M, Ferianis M. Experimental determination of the lifetime for the 2p3d(1P0) helium doubly excited state. PHYSICAL REVIEW LETTERS 2003; 90:153004. [PMID: 12732033 DOI: 10.1103/physrevlett.90.153004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2002] [Indexed: 05/24/2023]
Abstract
Two recent theoretical studies [C. Liu, Phys. Rev. A 64, 010501 (2001)]; M. Zitnik, ibid. 65, 032520 (2002)]] predict that the fluorescence lifetimes of helium doubly excited states converging to He+ N=2 should be longer than that of the He+ 2p ion state. This effect is caused by the electric field of the outer electron which, through Stark mixing, gives the inner fluorescing electron some series specific, stabilizing 2s character. We have obtained the first experimental evidence that confirms this effect by measuring the lifetime of the 2p3d(1P0) doubly excited state. This was determined to be 190+/-30 ps compared to 100 ps for the He+ 2p ion state. The measurements were performed using short pulses of synchrotron radiation to form doubly excited states and recording the arrival time of photons from fluorescence.
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Harries JR, Sullivan JP, Sternberg JB, Obara S, Suzuki T, Hammond P, Bozek J, Berrah N, Halka M, Azuma Y. Double photoexcitation of helium in a strong dc electric field. PHYSICAL REVIEW LETTERS 2003; 90:133002. [PMID: 12689282 DOI: 10.1103/physrevlett.90.133002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2002] [Indexed: 05/24/2023]
Abstract
We report the first experimental measurements of the effect of an applied field on the photoexcitation and autoionization of doubly excited states of helium. Ground-state photoionization spectra have been measured in the region below the He+(N=2) threshold with static electric fields of up to 84.4 kV/cm across the interaction region. The results are compared to the theoretical calculations of Chung et al. [J. Phys. B 34, 165 (2001)]], which are the only calculations available in this regime. Transitions to several states in the N=2, n=6 manifold are assigned, and a wealth of new structure is observed. Our data show that many more series are mixed in by the field than those predicted by theory.
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Affiliation(s)
- James R Harries
- Photon Factory, IMSS, KEK, 1-1 Oho, Tsukuba-shi, Ibaraki-ken, 305-0801 Japan
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10
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Penent F, Lablanquie P, Hall RI, Zitnik M, Bucar K, Stranges S, Richter R, Alagia M, Hammond P, Lambourne JG. Observation of triplet doubly excited states in single photon excitation from ground state helium. PHYSICAL REVIEW LETTERS 2001; 86:2758-2761. [PMID: 11290032 DOI: 10.1103/physrevlett.86.2758] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2000] [Indexed: 05/23/2023]
Abstract
We have observed, for the first time, LS-forbidden triplet doubly excited states, in single photon excitation of ground state helium, below the second ionization threshold. These states are identified as (3)D(o) and (3)P(o) and their excitation is due to spin-orbit interaction that mixes them with the optically allowed (1)P(o) states. This observation is possible due to the very high efficiency in detecting metastable atoms created after the fluorescence decay of the doubly excited states, and the new capabilities of third generation synchrotron vacuum ultraviolet sources with high resolution beam lines.
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Affiliation(s)
- F Penent
- DIAM, Université P. & M. Curie, 75252 Paris Cedex 05, France
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