Quenching of excited rubidium (52P) atoms in flames

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 SH2 = 3·6(±0·4) Å2, SN2 = 25(±1·5) Å2, SO2 = 83(±5) Å2 and SH2 O = 4·0(±0·8) Å2 respectively. In the derivation of the S-values it was assumed that SAr is negligibly small. The S-values for the diatomic molecules may be considered as valid for a temperature of about 1900°K, whole SH2O is valid at about 2100°K. The possibility of a resonance effect between the excited Rb-level and the molecular vibrational levels is discussed