SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: IX. ENERGY TRANSFER IN COLLISIONS BETWEEN SODIUM AND INERT GAS ATOMS

Abstract

The total cross sections for inelastic collisions between sodium and inert gas atoms, leading to 3 ²P_1/2 ↔ 3 ²P_3/2 excitation transfer in sodium, have been determined in a series of sensitized fluorescence experiments with sodium – inert gas mixtures. The sodium vapor was maintained at a pressure of 5 × 10⁻⁷ mm Hg, at which there is no trapping of the resonance radiation, and the inert gas pressures ranged from 0 to 1 mm Hg. The cross sections Q₁(3 ²P_1/2 → 3 ²P_3/2) and Q₂(3 ²P_1/2 ← 3 ²P_3/2) are as follows: Na–He, 86.0 and 44.8 Ų; Na–Ne, 67.0 and 35.4 Ų; Na–Ar, 110 and 55.9 Ų; Na–Kr, 85.0 and 43.6 Ų; Na–Xe, 89.8 and 45.6 Ų. The ratios Q₁/Q₂ are in agreement with the value predicted from the principle of detailed balancing and the cross sections also agree, as to order of magnitude, with some theoretically predicted values.