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Regular and chaotic multiphoton dissociation (EN)

Constantoudis, V (EN)
Nicolaides, CA (EN)

N/A (EN)

The rate of multiphoton dissociation of the BeH2+ molecule in its ground and first two excited vibrational levels has been computed via classical mechanics as a function of laser frequency. There is agreement with earlier quantum-mechanical results as regards the existence and magnitude of an optimal frequency, omega*, for which the dissociation rate is maximized. This fact has been analyzed and understood via the application of the theory of chaotic scattering. Indeed, we find fractal singularities in the function T-d(x) Of the duration of photodissociation, and we compute their dimension to be equal to 1, in agreement with the conjecture of Lan, Finn, and Ott [Phys. Rev. Lett. 66, 978 (1991)] that this must be a characteristic of systems exhibiting nonhyberbolic scattering. Turning to the problem of interpreting the appearance of an optimal omega*, we propose the following two mechanisms for the reduction of the multiphoton dissociation rate. First is the increase of fractal singularities when the frequency omega attains values larger than omega*. Second is the gradually increasing overlap of the classical initial state with the region of Kolmogorov-Arnold-Moser tori when omega<omega*. Finally, as the intensity is increased there is a transition from chaotic to regular photodissociation, where the singularities in T-d(x) are finite. It is conjectured that this reflects the emergence of the quantum-mechanical phenomenon of above-threshold dissociation. (EN)

journalArticle

DRIVEN MORSE OSCILLATOR (EN)
CLASSICAL DYNAMICS (EN)
EXCITATION (EN)
SINGULARITIES (EN)
FIELD (EN)
ATOMS (EN)
QUANTUM-THEORY (EN)
SCATTERING (EN)
LASER-INDUCED DISSOCIATION (EN)

Εθνικό Μετσόβιο Πολυτεχνείο (EL)
National Technical University of Athens (EN)

Physical Review A - Atomic, Molecular, and Optical Physics (EN)

1997


AMERICAN PHYSICAL SOC (EN)



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