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arXiv · 1807.07935

Power-law decay in the nonadiabatic photodissociation dynamics of alkali halides due to quantum wavepacket interference

Yuta Mizuno·Koji Hukushima
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Abstract

The nonadiabatic photodissociation dynamics of alkali halide molecules excited by a femtosecond laser pulse in the gas phase are investigated theoretically, and it is shown that the population of the photoexcited molecules exhibits power-law decay with exponent -1/2, in contrast to exponential decay, which is often assumed in femtosecond spectroscopy and unimolecular reaction theory. To elucidate the mechanism of the power-law decay, a diagrammatic method that visualizes the structure of the nonadiabatic reaction dynamics as a pattern of occurrence of dynamical events, such as wavepacket bifurcation, turning, and dissociation, is developed. Using this diagrammatic method, an analytical formula for the power-law decay is derived, and the theoretical decay curve is compared with the corresponding numerical decay curve computed by a wavepacket dynamics simulation in the case of lithium fluoride. This study reveals that the cause of the power-law decay is the quantum interference arising from the wavepacket bifurcation and merging due to nonadiabatic transitions.

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Yuta Mizuno, Koji Hukushima. 2018-09-10. Power-law decay in the nonadiabatic photodissociation dynamics of alkali halides due to quantum wavepacket interference. https://doi.org/10.1063/1.5048957

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