Computerised pulse-radiolysis system for gas-phase kinetics

Pulse-radiolysis equipment for studies of radical reaction kinetics in the gas phase is described. The equipment is built around an accelerator of the Febetron type for 800 keV electrons. The analysing light is pulsed with optical feedback regulation of the intensity to increase the luminosity ca. 50 times during the measurement. It is equipped with photoelectric detection of transient optical absorptions in the time interval 1 x 10-8 10-3 s of radicals in the wavelength range 200-900 mm. The stray-light level is low (<1%) even at 200 nm. The data collection system is computerised and controlled by a PC with hard- and software for recording transients and for setting the wavelength. Experimental measurements of the kinetics of decay of the CH3 radical in SF6 bath gas are in the interval ± 10% of the literature value. The equipment is intended for measurements of reaction kinetics related to combustion and atmospheric chemistry. (au) (13 refs.)