A theoretical study of the two-photon ionization of metastable He with linearly and circularly polarized laser light

Abstract

Generalized cross sections <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\hat{\sigma}_{L}</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\hat{\sigma}_{C}</tex> for the two-photon ionization of He from the metastable <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2^{1}S</tex> state are calculated for linearly and circularly polarized incident laser light, respectively, in the wavelength range 3725-5100 Å. Significant enhancement of cross sections occurs through real <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3^{1}P</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4^{1}P</tex> p intermediate states. The ratio <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\hat{\sigma}_{C}</tex> / <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\hat{\sigma}_{L}</tex> shows a minima at the wavelengths close to 3743 and 4450 Å.