Vibrationally excited populations from IR-multiphoton absorption. II. Infrared fluorescence measurements

Abstract

Infrared emission spectra were obtained for 1, 1, 2-trifluorethane (TFE) excited by infrared multiphoton absorption (1079.85 cm−1). The emission features show that the HF reaction product is formed in vibrational states up to about v=3. Furthermore, emission attributed to F–C≡C–H was observed near 3320 cm−1, indicating that the difluoroethylene primary products of TFE decomposition undergo secondary photolysis; since the difluoroethylene products at room temperature do not absorb laser light, they must be formed vibrationally excited. The emission from the C–H stretch modes of TFE was readily identified near 2980 cm−1 and the emission intensity was obtained as a function of laser fluence. These data are in excellent agreement with predictions based on the theoretical expression for fluorescence intensity and the reconstructed populations determined by the Master Equation calculations described in the preceding paper. These results provide additional support for the accuracy of the reconstructed population distributions and for the theory relating infrared fluorescence intensity to total vibrational energy in polyatomic molecules.