Lyman-.alpha. photometry: curve of growth determination, comparison to theoretical oscillator strength, and line absorption calculations at high temperature

Abstract

Absolute concentrations of H atoms in the absorption region of an atomic resonance photometer have been accurately determined with a chemical kinetic technique that is based on the H + NO2 reaction. Subsequently, the curve of growth for the Lyman- transition (H(SP/sub 3/2,1/2/) reverse arrow H(SS/sub 1/2/)) has been determined with a resonance lamp that is essentially a microwave-driven electrodeless lamp plasma. Additional experiments have been performed in order to measure the temperature and (H) in the resonance lamp plasma. Thus, simplified theoretical calculations of the curve of growth could be made from first principles using no adjustable parameters. These calculations agreed with experiment within experimental error, and therefore, the theoretical oscillator strength, as calculated from the known wave functions for H, is experimentally confirmed for the H(SP/sub 3/2,1/2) reverse arrow H(SS/sub 1/2/) transition. Confidence can now be placed in line absorption calculations and, hence, in measurements of (H), at high absorber temperatures such as those encountered in flames, plasmas, and shock tubes where the atomic resonance absorption spectroscopic (aras) technique is commonly used. 25 references, 9 figures, 4 tables.