Analysis of the decay of molecular fluorescence in optically excited mercury vapor

The decay of the 485 and 335 nm molecular fluorescence bands in optically excited mercury vapor is studied. A 10 nsec laser pulse at 256 nm is used to excite the vapor and the subsequent fluorescence intensity between 1 and 2000 μsec was recorded for each band. At late times following the laser pulse, both bands decay at the same exponential rate. This exponential decay coefficient was measured as a function of gas density from 1017 to 1019 cm−3 and as a function of temperature from 473 to 1048 °K. These decay data, as well as data on the relative intensities of the two bands, are analyzed in terms of a simple kinetic model for the mercury vapor system and various kinetic rates are determined. Some decay rates for the 6 3P atomic manifold are also obtained and compared with previous measurements.