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

Abstract

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.