Cross sections of collisional excitation transfer in collisions of rare-earth metal atoms in screened excited states with atoms of inert gases

Abstract

We present and apply a method to determine the collisional excitation transfer (CET) cross sections in collisions of rare-earth metal (REM) atoms in the screened excited states 4fN − 15d6s2 with ground-state atoms of inert gases. The method is based on the fact that the upper laser levels are collisionally populated from the close-lying resonant levels, which are excited by electron impact, in REM vapour lasers. An experimental measurement of only one laser parameter (average lasing power) is required to determine the cross sections. The CET cross sections from the screened level 4f12(3H5)5d3/26s2, with energy E = 22 791.176 cm−1, to the unscreened 4f12(3H6)6s26p1/2 (E = 22 468.046 cm−1) and screened 4f13(2F07/2)5d6s(3D) (E = 22 559.502 cm−1) levels of thulium atoms in the collisions with helium atoms are estimated as an example.