Photoassociation of atoms in ultracold collisions probed by wave-packet dynamics

Journal Article · Thu Dec 01 04:00:00 EST 1994 · Physical Review A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.50.5025· OSTI ID:7094838

Machholm, M; Giusti-Suzor, A; Mies, F H ^[1]

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1. Laboratoire de Photophysique Moleculaire, Batiment 213, Universite de Paris-Sud, 91405 Orsay Cedex (France) Department of Chemistry, H.C. Orsted Institute, 2100 Copenhagen O (Denmark) Laboratoire de Chimie Physique, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France) National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

Photoassociation in laser-assisted collisions of ultracold alkali atoms has been used recently to perform high-precision spectroscopy of very-long-range states. Rovibrational spectra close to the Na(3 [sup 2][ital S])+Na[sup *](3 [sup 2][ital P][sub 3/2]) dissociation limit have been obtained by monitoring an enhanced Na[sub 2][sup +] ion signal. We propose the use of pump-probe techniques to study the dynamics of the ionization process. At very large distances (typically 70 a.u.) two colliding Na atoms absorb a photon and form a coherent vibrational wave packet. We follow the packet in time and probe two possible mechanisms that are proposed to yield molecular ions: [ital photoionization], where the second photon is absorbed at a small internuclear distance [ital R] directly ionizing the molecule, and [ital associative] [ital ionization] with excitation at intermediate [ital R] to the nuclear continuum of a doubly excited state followed by a half collision and autoionization at small [ital R]. The latter event can also lead to dissociation of the complex. The two mechanisms lead to distinct differences in the ion signals as a function of delay time between the pump and the probe pulses. Estimates of the ion rates to be expected in actual pump-probe experiments are given, which tend to favor the autoionization mechanism as the dominant reaction path.

• OSTI ID: 7094838
• Journal Information: Physical Review A; (United States), Journal Name: Physical Review A; (United States) Vol. 50:6; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

664300* -- Atomic & Molecular Physics-- Collision Phenomena-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ALKALI METALS
ATOM COLLISIONS
ATOM-ATOM COLLISIONS
BEAM COOLING
BOUND STATE
CHARGED PARTICLES
COLLISIONS
DIMERS
DYNAMICS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
EXCITED STATES
EXPERIMENT PLANNING
IONIZATION
IONS
LASER RADIATION
MECHANICS
METALS
MOLECULAR IONS
MOMENTUM COOLING
PHOTOIONIZATION
PLANNING
RADIATIONS
ROTATIONAL STATES
SODIUM
STOCHASTIC COOLING
VIBRATIONAL STATES
WAVE PACKETS