The interaction of excited states of barium with xenon atoms determined by spectral-line contour measurements

The wings of barium absorption lines for the series 6s 2 1 S 0 -6snp 1 P 1 (n=7-11) have been measured with high resolution for barium in the presence of less than an atmosphere of xenon in the temperature range 1000-1100K. Tables of normalised linewing-spectra are presented. These spectra were analysed with both the unified Franck-Condon theory and a numerical evaluation of the correlation function of semiclassical line-broadening theory. Both analyses lead to similar barium-xenon potentials for these excited states, and demonstrate that the intense regions in the line wings arise from collisions occurring when the perturbing atom has penetrated within the valence-electron charge-density maximum of the excited barium atom. Comparisons of the potentials derived from these line contours are made with available calculations.