Quantum yield measurement in the chemical reactions of laser-excited Zn and Rb atoms with molecules

In the present paper, we introduce a method for measuring the apparent quantum yield theta(ap) and the rate-constant values of the physical k(p) and chemical k(c) quenching of electronically excited Zn and Rb atoms by gas molecules. The method is based on measuring the concentration of the atoms at the end of their. flow in a mixture with a reagent-gas and a carrier gas, in the region where all quenching and secondary processes are already over. The concentration of the atoms was determined from measured absorbed energy of resonance laser radiation. The rate constants and the cross-sections of the chemical and physical quenching of Zn ((3)P(1)(0)) and Rb(11P(3/2)) atoms with several molecules have been determined. For some collisions the quantum yield was found to be close to unity. The method may. find applications in laser photochemical isotope separation and in measuring the rate constants of reactions proceeding with participation of ground state atoms. (C) 2010 Elsevier B. V. All rights reserved.