Floquet representation of absolute phase and pulse-shape effects on laser-driven molecular photodissociation

Journal Article · Tue Feb 01 04:00:00 EST 2005 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.71.023403· OSTI ID:20650099

Nguyen-Dang, T T; Lefebvre, C; Abou-Rachid, H; Atabek, O ^[1]

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1. Departement de Chimie, Universite Laval, Quebec, Quebec, G1K 7P4 (Canada)

Using a recent reformulation of Floquet theory [S. Guerin and H. R. Jauslin, Adv. Chem. Phys. 125, 1 (2003)], we discuss the dynamical role of the absolute phase in the photofragmentation of molecules subjected to laser pulses. We show how the dependence of Floquet states on an absolute phase is related to the complexity of the dressed molecular scheme and to the multiphoton character of the molecular dynamics. The general theory is applied to the study of the photodissociation of H{sub 2}{sup +} in a 400-nm periodic laser pulse, repeated with a frequency lying in the IR. The dependence of the dynamics on the phase of the pulse envelope is highlighted through an effect previously called dynamical dissociation quenching (DDQ) [F. Chateauneuf et al., J. Chem. Phys. 108, 3974 (1998)] and through photofragment kinetic energy spectra. These spectra allow us to map out the Floquet content of the dynamics - i.e., its multiphoton character both with respect to the carrier-wave frequency, which gives rise to the usual bond-softening mechanism, and with respect to the pulse modulation frequency in the IR. The synchronization of this pulse modulation with the wave packet motion governs the DDQ effect in this uv-visible pulsed excitation case.

• OSTI ID: 20650099
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 2 Vol. 71; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
DISSOCIATION
ENERGY SPECTRA
EXCITATION
HYDROGEN IONS 2 PLUS
KINETIC ENERGY
LASER RADIATION
MODULATION
MOLECULAR DYNAMICS METHOD
MOLECULES
MULTI-PHOTON PROCESSES
PERIODICITY
PHOTON-MOLECULE COLLISIONS
PULSES
QUENCHING
SYNCHRONIZATION
WAVE PACKETS