UF6 photodissociation through measurement of visible and infrared luminescence.

Abstract

Infrared multiple-photon dissociation of UF6 was induced at room temperature by irradiation simultaneously with optically pumped CF4 laser at 615 cm−1 and TEA CO2 laser at 1,073 cm−1. The dissociation of UF6 was verified from evidence of fluorine generation, obtained by its reduction with H2 and observing infrared emission from the resulting excited HF molecules. The rate of UF6 dissociation was determined from the decrease of infrared absorption shown by UF6. Quantitative indication of the dissociation yield of UF6 is known to be provided by the more readily measurable visible luminescence from the irradiated zone. The intensity of the visible luminescence was therefore measured, to seek the dependence of dissociation yield on such factors as the fluences of the CF4 and CO2 lasers, and the pressures of UF6 and of Ar buffer gas. A clear threshold proved to exist around 70 J/cm2 for the fluence of CO2 laser, but not for that of the CF4 laser, indicating that a very slight excitation by the latter laser serves to induce UF6 dissociation. This suggests that the dissociation energy is supplied in large part by the COZ laser. In the range of UF6 dissociation, the visible luminescence intensity was found to rise roughly proportionally with CF4 and CO2 laser fluences, as well as with the pressures of UF6 and of added Ar buffer gas.