Photoabsorption profile and satellite features of the potassium4s→4ptransition perturbed by ground-state helium atoms

Abstract

Quantal calculations are performed to determine the absorption profile of the broadened potassium resonance line 4p ← 4s in its far wings provoked by helium perturbers. First, the X 2 � + , A 2 �, and B 2 � + potentials, as well as the transition dipole moments, are carefully computed through ab initio methods, based on stateaveraged complete active space self-consistent field multireference configuration interaction (SA-CASSCFMRCI) calculations involving the Davidson and basis-set superposition error (BSSE) corrections. The data are then used to generate the KHe photoabsorption spectra and to examine their behavior with temperature. The theoretical profile is dominated by the free-free transitions and exhibits, in the vicinity of the wavelength position of 693 nm, a satellite peak in the blue wing attributed to the B ← X transitions. The results are compared with previous theoretical and experimental investigations and, in general, good agreement is found.