Continuum radiation and potentials of Na–noble gas molecules

Abstract

The normalized emission spectra resulting from the perturbation of Na atoms by 1–1000 Torr of noble gas have been measured in the range 10–150 nm about the 589 nm resonance line. This spectrum, due to the A–X and B–X transitions of the Na–noble gas molecules, was measured with 1.5 nm resolution. The Na, in a cell at a temperature of 417±5 °K, was optically pumped to the 3 ²P_1/2 and 3 ²P_3/2 states by resonance radiation. The resulting emission was measured at several Na densities to obtain the normalized emission spectra in the limit of zero radiation entrapment. Using the Franck–Condon principle, or equivalently the quasistatic theory of line broadening, and density factors, the A ²Π_1/2,3/2 and X ²Σ_1/2 state potentials for NaAr, NaKr, and NaXe have been obtained from the pressure dependence of the spectra. Continuum absorption and emission coefficients for these molecules, obtained by application of the same theories, are also presented. The analysis identifies the low pressure limit of the spectrum as due to free collision states above the angular momentum barrier. The population factors corresponding to quasibound, orbiting resonances are evaluated and used in this analysis.