Dissociation of H{sub 2}{sup +} in intense femtosecond laser fields studied by coincidence three-dimensional momentum imaging

Journal Article · Sun Oct 15 04:00:00 EDT 2006 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.74.043411· OSTI ID:20863931

Wang, P Q; Sayler, A M; Carnes, K D; Xia, J F; Smith, M A; Esry, B D; Ben-Itzhak, I ^[1]

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1. J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)

The dissociation of H{sub 2}{sup +} in an intense laser field has been experimentally studied using femtosecond laser pulses at 790 nm in the intensity range of 10{sup 13}-10{sup 15} W/cm{sup 2}. Kinematically complete measurements of both the ionic H{sup +} and neutral H fragments dissociated from a vibrationally excited H{sub 2}{sup +} beam have been achieved by a coincidence three-dimensional momentum imaging system. Angular-resolved kinetic energy release spectra for a series of different intensity ranges have been obtained using the intensity-difference spectrum method, thus disentangling the problem caused by the intensity volume effect. Our results indicate that the dissociation dynamics are drastically different for 'long' (135 fs) and 'short' (45 fs) laser pulses at similar high laser intensities. Specifically, bond softening is found to be the main feature in long pulses, while above threshold dissociation is dominant in short pulses whose durations are comparable with the vibrational period of the molecule. Bond softening in short pulses appears at low kinetic energy release with a narrow angular distribution. The experimental results are well interpreted by solving the time-dependent Schroedinger equation in the Born-Oppenheimer representation without nuclear rotation.

• OSTI ID: 20863931
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 74; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR DISTRIBUTION
BORN-OPPENHEIMER APPROXIMATION
CHEMICAL BONDS
DISSOCIATION
HYDROGEN IONS 1 PLUS
HYDROGEN IONS 2 PLUS
KINETIC ENERGY
LASER RADIATION
LASERS
MOLECULES
PHOTOLYSIS
PHOTON-MOLECULE COLLISIONS
PULSES
ROTATION
SCHROEDINGER EQUATION
THREE-DIMENSIONAL CALCULATIONS
TIME DEPENDENCE
VIBRATIONAL STATES