Collision induced absorption spectra and line broadening of CsRg system (Rg=Xe, Kr, Ar, Ne) studied by the symmetry adapted cluster‐configuration interaction (SAC‐Cl) method

The collisionally induced absorption process and the broadening of the 6P resonance line of the Cs–Rg system (Rg=Xe, Kr, Ar, and Ne) are studied theoretically by the symmetry adapted cluster‐configuration interaction (SAC‐CI) method. The potential energy curves and the transition moments of the CsRg system correlating to the 6S, 6P, 5D, and 7S states of the Cs atom are investigated. The reduced absorption coefficients are calculated using the quasistatic approximation and the results agree well with the experimental data. The monotonic dependence of the spectral peaks on the rare gas species is due to the similar monotonic dependence of the avoided crossing point between the 7sΣ and 5dΣ states. The absorption intensities decrease as the rare gas atom is substituted from Xe to Ne in agreement with the experimental observation. The intensities of the 6sΣ–5dΣ transitions are calculated to be larger than those of the 6sΣ–7sΣ ones, since the former transitions are induced at larger internuclear distances than the latter.