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

Abstract

The total cross sections for excitation transfer between the 6²P_1/2and 6²P_3/2levels in cesium, induced by collisions of the second kind between cesium and inert gas atoms, have been determined using methods of sensitized fluorescence. The experiments were carried out at a cesium vapor pressure of 1 × 10⁻⁶ mm Hg, at which there is no trapping of resonance radiation, and over a range of inert gas pressures extending from 1 to 300 mm Hg. The cross sections Q₁(²P_1/2 → P_3/2) and Q₂(²P_1/2 ← ²P_3/2) are as follows: Cs–He: 5.7 × 10⁻²¹and 3.9 × 10⁻²⁰ cm²; Cs–Ne: 1.9 × 10⁻²¹and 3.1 × 10⁻²⁰ cm²; Cs–A: 1.6 × 10⁻²¹and 5.2 × 10⁻²⁰ cm²; Cs–Kr: 8.3 × 10⁻²¹and 18.4 × 10⁻²⁰ cm²; Cs–Xe: 7.2 × 10⁻²¹and 27.4 × 10⁻²⁰ cm². A mechanism for the excitation transfer is suggested, which involves an interaction between the inert gas atoms and the 6²P electron in cesium, behaving as a free particle.