Optical Properties of Gaseous 2,4,6-Trinitrotoluene in the Ultraviolet Region

Abstract

The absorption spectrum of gaseous 2,4,6-trinitrotoluene (TNT) was recorded by conventional absorption spectroscopy (AS) as well as cavity ringdown spectroscopy (CRDS) methods in the spectral regions 195–300 and 225–235 nm, respectively. These spectra were normalized by using the saturated TNT vapor-number density for the measured cell temperature to obtain the absorption cross section of TNT. No spectral features were found in the spectra; this result is consistent with a repulsive electronic excited state of TNT. The temperature dependence of the absorption coefficient of saturated TNT vapor was measured within the temperature range 5–110 °C. The limit of detection of TNT vapor by CRDS is less than 1 ppb. Real-time CRDS measurements of the TNT vapor density at 21 and 37 °C are presented. The TNT evaporation rates were found to be 7 × 108 and 4 × 1010 molecules/cm2 × s at 21 and 37 °C, respectively.