Strong-field photoionization of O{sub 2} at intermediate light intensity

Journal Article · Wed Sep 15 04:00:00 EDT 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.82.033431· OSTI ID:21450598

Kloda, Tomasz; Linusson, Per; Hansson, Tony ^[1]; Matsuda, Akitaka ^[2]; Karlsson, Hans O ^[3]; Elshakre, Mohamed ^[4]; Eland, John H. D. ^[5]; Feifel, Raimund ^[6]

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1. Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden)
2. Institute for Molecular Science, National Institute of Natural Sciences, Myodaiji, Okazaki, Aichi 444-8585 (Japan)
3. Department of Physical and Analytical Chemistry, Quantum Chemistry, Uppsala University, Box 518, SE-751 20 Uppsala (Sweden)
4. Department of Chemistry, Cairo University, 126 13 Cairo (Egypt)
5. Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom)
6. Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden)

We investigated by electron spectroscopy the strong-field multiphoton ionization of O{sub 2} molecules with ultrashort laser pulses in the intensity range between the multiphoton and tunneling regimes. The ionization proceeds by at least three different mechanisms, in addition to the eight- and nine-photon nonresonant pathways. Transient multiphoton resonances with vibrational Rydberg levels give rise to direct Freeman-type peaks with sublaser linewidth and spin-orbit splitting. Some resonance levels actually become populated and yield extremely narrow lines because of postpulse vibrational autoionization. When the lowest photon order resonance channel for the Rydberg states is closed, a third contribution becomes dominant with a main peak at 0.4 eV that shares its main properties with the recently discovered universal low-energy structure in the electron spectra of atoms and molecules [C. I. Blaga et al., Nat. Phys. 5, 335 (2009); W. Quan et al., Phys. Rev. Lett. 103, 093001 (2009)]. The variation of the Freeman resonance spectrum with the laser peak intensity is well correlated with the vibronic Franck-Condon factors for the overlap of the intermediate Rydberg state with the O{sub 2} ground state. Accordingly, the Freeman peaks could be unambiguously assigned to individual vibronic multiphoton resonances, and the disappearance of the Freeman resonances at a certain laser intensity could be explained. The population of the autoionizing Rydberg states could be assigned similarly to such vibronic resonances.

• OSTI ID: 21450598
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 3 Vol. 82; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR MOMENTUM
ATOMS
AUTOIONIZATION
BOSONS
COLLISIONS
ELECTROMAGNETIC RADIATION
ELECTRON SPECTRA
ELECTRON SPECTROSCOPY
ELEMENTARY PARTICLES
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
EV RANGE
EXCITED STATES
IONIZATION
MASSLESS PARTICLES
MOLECULE COLLISIONS
MOLECULES
MULTI-PHOTON PROCESSES
NONMETALS
ORBITS
OXYGEN
PARTICLE PROPERTIES
PHOTOIONIZATION
PHOTON COLLISIONS
PHOTON-MOLECULE COLLISIONS
PHOTONS
PULSES
RADIATIONS
RESONANCE
RYDBERG STATES
SPECTRA
SPECTROSCOPY
SPIN
TRANSIENTS
TUNNEL EFFECT
VISIBLE RADIATION