Quantal studies of alkali-metal-rare-gas collisions. III. Broadening of Na D lines by He

Abstract

For pt.II see ibid., vol.8, no.14, p.2393 (1975). Fully quantal calculations of the width and shift of the Na D double due to collision with He(¹S) in the temperature range 400K<or=T<or=3500K are presented. This is the first time that Baranger's fully quantal impact theory (1962) has been applied to the broadening of spectral lines by neutral perturbers. The complex cross section is opacity analysed and the complex opacity functions are studied as a function of l. The statistical approximation can be used at low l and can reproduce the total width with the cut-off impact parameter decreasing with increasing temperature. Inelastic processes contribute significantly to the width. The shift is an order of magnitude smaller than the width.