Topical Meeting on Laser Techniques in the Extreme Ultraviolet

Spectroscopic Measurements of Sub-Laser Linewidth Autoionization Rates

William E. Cooke, S A Bhatti, Christopher L. Cromer

Published Jan 1, 1982• 0 citations

Abstract

If the lifetime of an autoionizing state is much shorter than the pulse length of the laser exciting it, then it is possible, with sufficient laser power, to ionize the entire atomic population. When the laser is tuned off resonance, it may still have sufficient power to ionize almost the entire population. The detuning at which the ionization efficiency will drop to 50% depends on the product of the laser pulse's energy density and the excited state's autoionizing rate.

DOI: 10.1364/euvs.1982.ma3

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Topical Meeting on Laser Techniques in the Extreme Ultraviolet

Spectroscopic Measurements of Sub-Laser Linewidth Autoionization Rates

William E. Cooke, S A Bhatti, Christopher L. Cromer

Published Jan 1, 1982• 0 citations

Publisher

Abstract

DOI: 10.1364/euvs.1982.ma3

Related papers

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Physical Review LettersMar 28, 197739 citations

A two-laser theory is formulated for the photoionization of Li atoms. The first laser is tuned above the ionization threshold of

\mathrm{Li}(2s)

. The second laser probes the ionized target. Stimulated recombination into

\mathrm{Li}(\mathrm{ns})

occurs near the Raman-type resonance point ${\ensuremath{\epsilon}}_{\mathrm{ns}}\ensuremath{-}{\ensuremath{\epsilon}}_{2s}\ensuremath{-}{\ensuremath{\epsilon}}_{1}+{\ensuremath{\epsilon}}_{2}=0$ (where

n>2

and ${\ensuremath{\epsilon}}_{q}$ is a photon energy). Near the resonance point the ionization probability is characterized by a line profile which resembles that for an autoionizing resonance.

A rigorous evaluation of the time evolution amplitude

G(t)

for an isolated autoionizing state has yielded the result ${{|G(t)|}^{2}}_{t\ensuremath{\rightarrow}\ensuremath{\infty}}={e}^{\ensuremath{-}\frac{\ensuremath{\Gamma}t}{\ensuremath{\hbar}}+\frac{{\ensuremath{\hbar}}^{2}}{{\ensuremath{\pi}}^{2}(4{E}^{2}+{\ensuremath{\Gamma}}^{2}){t}^{2}}}$ where

E

is the energy above the ionization threshold and $\ensuremath{\Gamma}$ the width. For states with lifetimes in the region ${10}^{\ensuremath{-}8}$-${10}^{\ensuremath{-}11}$ sec near the ionization threshold, the nonexponential decay corrections are sufficiently large to suggest that perhaps it is possible to test the validity of the fundamental exponential "law" within the realm of atomic physics.