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Physical Review A

Effect of continuum-continuum and quasibound-continuum above-threshold transitions on (1+1)-photon resonance-enhanced multiphoton autoionization

Krishna Rai Dastidar

Published Apr 1, 1996• 2 citations
Publisher

Abstract

We have studied the effect of above-threshold transitions on the (1+1)-photon resonance-enhanced ionization and autoionization processes. We have shown that the effect of the photoionization decay of the autoionizing (AI) state to the higher continuum becomes dominant when the photoionization width of the AI state is comparable to or larger than the autoionization width to within an order of magnitude, i.e., for the intermediate range of laser intensity. The continuum-continuum coupling and the higher-order transitions become effective only for much higher values of the above-threshold transition strengths, i.e., for much higher values of the laser intensity. \textcopyright{} 1996 The American Physical Society.

DOI
10.1103/physreva.53.2881

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We know that the Fano profile is obtained for single-photon absorption to the ionization continuum in the presence of an autoionizing state. We have shown that, in the case of (1+1)-photon absorption to an autoionizing state embedded in the ionization continuum, the absorption profile changes radically to a mirror image of the Fano profile for the value of q=\ifmmode\pm\else\textpm\fi{}1, q being the Fano q parameter. Moreover, for higher values of q, the (1+1)-photon absorption profile exhibits a broad minimum, while a distinct interference pattern is obtained in the profile of single-photon absorption. The absorption line shape has been found to oscillate between the Fano and a modified Fano profile for the autoionization through odd and even number of steps, respectively, via resonances.
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