Investigation of the fluorescence of molecular iodine in the 340 nm band

Results are presented of observations of the fluorescence of iodine vapor, subjected to cw optical pumping, as a function of the temperature and pressure of the SF₆, N₂, Ar, Xe, He, and Kr buffer gases. It is shown that an increase of the fluorescence in the 340 nm band with rising buffer gas pressure is accompanied by a decrease in the iodine fluorescence in the 250–330 nm band. The efficiency of the action of the buffer gas depends on its molecular weight and on the wavelength of the exciting light. The intensity depends on the buffer gas used. An estimate is made of the rate of quenching of the fluorescence by iodine molecules in the ground state k_qτ =(3.0±0.30)×10^–18 cm³. For Xe, k_qτ = (1.2±0.6)×10^–18 cm³. It is shown that the fluorescence quantum efficiency η does not depend on the mixture temperature up to 425 °C. The value of η for optical pumping (λ = 190 nm) of a mixture of iodine vapor and 5 atm SF₆ is η = 0.04±0.02 and for a mixture with 1.5 atm Ar, is η = 0.05±0.02.