Photodestruction of organic compounds exposed to pulsed VUV irradiation

摘要

Abstract: Along with the excimer lasers, the pulsed argon lamps with MgF$-2$/ windows can be used for photodestruction of organic compounds. The lamps were used in experiments for photocleaning of the optical materials surfaces and photoetching of the submicron PMMA films. The irradiation was carried out in air, the test samples being placed 10 to 100 $mu@m apart from the light source window surface. The following specific features were observed: high degree of molecular oxygen dissociation in the microgap, pulsed heating of air and pressure rise in the microgap, causing ejection of the photodestruction products, and pulsed radiation heating of the organic compound which can result in the diffusion flux growth of the volatile fragments of the irradiated test sample. The kinetics of accumulation of the double C $EQ C bonds was measured by the change in transmission of the submicron PMMA films at $lambda $EQ 200 nm. The photomodification results in a considerable decrease of the film substance ejection. The pulsed VUV irradiation is shown to be a simple and efficient technique for photocleaning of the surface layers of the optical materials removing hydrocarbon compounds.!