Fluorescence of Nitrogen Dioxide

Abstract

The mean lifetime of fluorescence of NO2 vapor was measured at pressures in the range 12 to 0.6 microns by a direct electronic method. A linear dependence of lifetime on pressure was found, and extrapolation to zero pressure gave 44 microseconds for the lifetime in absence of collisions. The fluorescence spectrum in the region 4600—8000 A was photographed with 4358 and 5461 A excitation, with somewhat different results. Interpretation of the results appears to require two excited electronic levels, one of which is not connected optically with the normal state and which is responsible for the long-lived fluorescence.