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Journal of Physics B Atomic and Molecular Physics

Theory of N-photon ionisation with short laser pulses

W A McClean, S. Swain

Published Sep 14, 1978• 14 citations
Publisher

Abstract

An expression for the N-photon ionisation probability for a many-level atom is obtained as a function of the laser pulse duration, t. It is shown that the leading term in the power series expansion is of order t 2N-1 . The relevance of these calculations to some recent experiments by Lompre et al. (1976, 1977) is discussed.
DOI
10.1088/0022-3700/11/17/005

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An expression is derived for the amount of two-photon ionisation produced by sub-nanosecond laser pulses under resonance conditions. On this time scale damping effects can be neglected and the ionisation probability becomes proportional to the cube of the pulse duration. A similar prediction for resonance multiphoton processes of higher order leads to a qualitative agreement with recent experimental observations. Finally, it is demonstrated that the same result can be obtained from a simple analysis of a two-step model.
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