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Title: Multiphoton excitation and ionization by elliptically polarized, intense short laser pulses: Recognizing multielectron dynamics and doorway states in C{sub 60} vs Xe

Abstract

Ionization and fragmentation of C{sub 60} fullerenes are studied by time-of-flight mass spectrometry, in elliptically polarized femtosecond laser fields at 797 nm of intensities I{sub 0}=(0.5-4.3)x10{sup 14} W cm{sup -2}. Xe atoms serve as a test case. We derive a qualitative theory describing such polarization studies. It turns out that polarization dependence can very sensitively distinguish single active electron (SAE) and multiple active electrons dynamics. In the case of Xe a clear signature of SAE dynamics is observed, with very pronounced changes in the ion yield as a function of ellipticity, indicative of N=5-8 and 18-22 photon processes for Xe{sup +} and Xe{sup 2+}, respectively. In contrast, only a moderate polarization dependence is observed in the C{sub 60} case, although at least 5 h{nu} photons at 797 nm are needed to generate C{sub 60}{sup +} and additional 11 for C{sub 60}{sup 2+}. At lower intensities, a moderate reduction in the ion yield for circular polarization establishes a two-photon SAE absorption process, connected with the key role of the lowest unoccupied molecular orbital (LUMO)+1(t{sub 1g}) as 'doorway state'. The absence of any polarization effect at 399 nm corroborates this finding. At high intensities enhanced fragmentation is observed, which is tentatively attributedmore » to returning loops of electron trajectories by the combined action of the C{sub 60}{sup +} field and the circularly polarized laser field - in contrast to conventional wisdom that linear polarization should lead to an enhanced recolliding electron yield. No sign of a pronounced multiphoton polarization signature with five and more photons is seen for C{sub 60} which would be predicted by the SAE picture - although the slopes of the ion yield as a function of intensity are given by the corresponding power laws {proportional_to}I{sub 0}{sup N}. This is taken as clear evidence of multielectron dynamics after reaching the doorway state.« less

Authors:
; ; ;  [1]
  1. Max Born Institute, Max-Born-Str. 2a, D-12489 Berlin-Adlershof (Germany)
Publication Date:
OSTI Identifier:
21304712
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 79; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.79.053414; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ELECTRON-MOLECULE COLLISIONS; ELECTRONS; EXCITATION; FULLERENES; LASER RADIATION; LASERS; MASS SPECTRA; MASS SPECTROSCOPY; MOLECULAR ORBITAL METHOD; MULTI-PHOTON PROCESSES; PHOTOIONIZATION; PHOTOLYSIS; PHOTON-MOLECULE COLLISIONS; PHOTONS; POLARIZATION; TIME-OF-FLIGHT METHOD; XENON IONS; YIELDS

Citation Formats

Shchatsinin, I, Ritze, H -H, Schulz, C P, and Hertel, I V. Multiphoton excitation and ionization by elliptically polarized, intense short laser pulses: Recognizing multielectron dynamics and doorway states in C{sub 60} vs Xe. United States: N. p., 2009. Web. doi:10.1103/PHYSREVA.79.053414.
Shchatsinin, I, Ritze, H -H, Schulz, C P, & Hertel, I V. Multiphoton excitation and ionization by elliptically polarized, intense short laser pulses: Recognizing multielectron dynamics and doorway states in C{sub 60} vs Xe. United States. https://doi.org/10.1103/PHYSREVA.79.053414
Shchatsinin, I, Ritze, H -H, Schulz, C P, and Hertel, I V. Fri . "Multiphoton excitation and ionization by elliptically polarized, intense short laser pulses: Recognizing multielectron dynamics and doorway states in C{sub 60} vs Xe". United States. https://doi.org/10.1103/PHYSREVA.79.053414.
@article{osti_21304712,
title = {Multiphoton excitation and ionization by elliptically polarized, intense short laser pulses: Recognizing multielectron dynamics and doorway states in C{sub 60} vs Xe},
author = {Shchatsinin, I and Ritze, H -H and Schulz, C P and Hertel, I V},
abstractNote = {Ionization and fragmentation of C{sub 60} fullerenes are studied by time-of-flight mass spectrometry, in elliptically polarized femtosecond laser fields at 797 nm of intensities I{sub 0}=(0.5-4.3)x10{sup 14} W cm{sup -2}. Xe atoms serve as a test case. We derive a qualitative theory describing such polarization studies. It turns out that polarization dependence can very sensitively distinguish single active electron (SAE) and multiple active electrons dynamics. In the case of Xe a clear signature of SAE dynamics is observed, with very pronounced changes in the ion yield as a function of ellipticity, indicative of N=5-8 and 18-22 photon processes for Xe{sup +} and Xe{sup 2+}, respectively. In contrast, only a moderate polarization dependence is observed in the C{sub 60} case, although at least 5 h{nu} photons at 797 nm are needed to generate C{sub 60}{sup +} and additional 11 for C{sub 60}{sup 2+}. At lower intensities, a moderate reduction in the ion yield for circular polarization establishes a two-photon SAE absorption process, connected with the key role of the lowest unoccupied molecular orbital (LUMO)+1(t{sub 1g}) as 'doorway state'. The absence of any polarization effect at 399 nm corroborates this finding. At high intensities enhanced fragmentation is observed, which is tentatively attributed to returning loops of electron trajectories by the combined action of the C{sub 60}{sup +} field and the circularly polarized laser field - in contrast to conventional wisdom that linear polarization should lead to an enhanced recolliding electron yield. No sign of a pronounced multiphoton polarization signature with five and more photons is seen for C{sub 60} which would be predicted by the SAE picture - although the slopes of the ion yield as a function of intensity are given by the corresponding power laws {proportional_to}I{sub 0}{sup N}. This is taken as clear evidence of multielectron dynamics after reaching the doorway state.},
doi = {10.1103/PHYSREVA.79.053414},
url = {https://www.osti.gov/biblio/21304712}, journal = {Physical Review. A},
issn = {1050-2947},
number = 5,
volume = 79,
place = {United States},
year = {2009},
month = {5}
}