Kinetic studies for advanced iodine laser concepts

Abstract

Singlet oxygen generators for COIL devices that involve discharge or optical excitation are currently being investigated. These generators deliver relatively high yields of O 2 (b 1 Σ + ) as the flows do not contain water vapor. In addition, discharge generators provide high concentrations of O atoms. Dissociation of I2 by the reagent streams from these generators will follow different kinetic pathways than those that are most important when the flow from a chemical generator is used. To provide a basis for understanding the dissociation kinetics that will be relevant for discharge and optically driven COIL devices we have examined the quenching of O 2 (b) and O 2 (a) by I 2 . Dissociation of I 2 by atomic oxygen and I*+O quenching have also been investigated. The primary findings are: (1) Quenching of O 2 (b) by I 2 is fast (5.8x10 -11 cm 3 s -1 ) with a branching fraction of 0.4 for the channel O 2 (b)+I 2 →O 2 (a)+I 2 . (2) Quenching of O 2 (a) by I 2 is too slow (k -16 cm 3 s -1 ) to be the initiation step in the I 2 dissociation process. (3) O 2 (a) is generated when I 2 is dissociated by O atoms. (4) The upper bound for the rate constant for quenching of I* by O atoms is k -12 cm 3 s -1 .