Oscillator Strengths and Rare-Gas-Induced Broadening of the Principal Series Lines of Ba

Abstract

Oscillator strengths have been determined for 23 transitions from the ground level of Ba relative to that of the resonance line by the hook method. The results are in good agreement with other experimental values. Rate coefficients of He-, Ar- and Kr-induced broadening have been measured for 6s^{2 1}S₀-6snp ¹P₁ (n=7 to 10), 6s^{2 1}S₀-5dnp ¹P₁ (n=6 and 7), and 6s^{2 1}S₀-5d7p ³D₁ and ³P₁ by the total absorption method. We find that, generally, the rate coefficient increases monotonously to its maximum value and then decreases with the effective principal quantum number of the upper level relative to the first ionization limit. For 6s^{2 1}S₀-5d7p ³P₁ and ³D₁, the rate coefficients deviate from this tendency and show minimum values. This singularity is explained qualitatively on the basis of the Fermi potential model by taking account of the configuration mixing.