Quenching of excited rubidium (5 2P) atoms in flames

Abstract

An alternating current photoelectric device (compare the work of Boers, (1) Hooymayers et al (2-4) and Hooymayers (5)) has been used for determining the yield factor p of resonance fluorescence for the infrared rubidium doublet (7800/7947 Å). From the p-values measured in five different hydrogen flames at about 2000°K and 1 atm pressure, the specific effective quenching cross-sections (2-5) S of the excited Rb atoms in collision with some molecules could be derived. The cross section values for these molecules were found to be S H 2 = 3·6(±0·4) Å 2, S N 2 = 25(±1·5) Å 2, S O 2 = 83(±5) Å 2 and S H 2 O = 4·0(±0·8) Å 2 respectively. In the derivation of the S-values it was assumed that S Ar is negligibly small. The S-values for the diatomic molecules may be considered as valid for a temperature of about 1900°K, whole S H 2O is valid at about 2100°K. The possibility of a resonance effect between the excited Rb-level and the molecular vibrational levels is discussed.