Showing papers by "Rodney S. Ruoff published in 1984"
TL;DR: In this article, the authors investigated the IR laser induced fluorescence from C-H stretch fundamentals, combination bands, and overtones in the region from 2800 to 3050 cm−1.
Abstract: Intramolecular vibrational energy transfer in isolated gas phase molecules of dimethyl ether has been studied by spectrally resolving the IR laser induced fluorescence from C–H stretch fundamentals, combination bands, and overtones in the region from 2800 to 3050 cm−1. By comparing the experimentally observed relative energy content of the IR active modes with that calculated from a statistical model it is concluded that the C–H stretches are strongly mixed with nearby bath states. The observed energy content distribution is best described by a statistical model which assumes coupling over a 20 cm−1 range. Dilution factors for the various C–H stretch modes were observed which vary from 0.01 to 0.20. These values are dependent on the rotational state excited. The experiments are performed by exciting a molecule cooled in a nozzle expansion with light from an infrared optical parametric oscillator. The fluorescence spectra are recorded with a cryogenic Michelson interferometer.
34 citations
TL;DR: In this paper, the authors compared the experimentally observed relative energy content of the IR active modes with that calculated from a statistical model, and concluded that substantial randomization of the energy initially deposited in the zeroth order optically excited state occurs.
Abstract: Intramolecular vibrational energy transfer in isolated gas phase molecules of dioxane has been studied by spectrally resolving the IR laser induced fluorescence from C–H stretch fundamentals, combination bands, and overtones in the region from 2800 to 3000 cm−1. By comparing the experimentally observed relative energy content of the IR active modes with that calculated from a statistical model it is concluded that substantial randomization of the energy initially deposited in the zeroth order optically excited state occurs. This statistical distribution differs from a thermal distribution due to fluctuations in the local state density. The energy content distribution is best described by the model if coupling over a range of 4 cm−1 is assumed. Dilution factors for the various C–H stretch modes were observed which vary from 0.018 to 0.13. These values are dependent on the rotational state excited. Collisional time dependent spectra of several relaxed modes are presented. The experiments are performed by ex...
22 citations
TL;DR: In this paper, the authors observed the first case of state selected ground electronic state intramolecular conformational interconversion in an isolated molecule by spectrally resolving the infrared laser induced fluorescence from CH stretch fundamental excitation of methyl vinyl ether.
Abstract: Molecules exhibiting conformational isomerism have been studied by spectrally resolving the infrared laser induced fluorescence from CH stretch fundamental excitation of methyl vinyl ether and from CH stretch fundamental and N=O overtone excitation of methyl nitrite. By comparison of the resolved fluorescence spectra of methyl vinyl ether with its absorbance spectrum, we have observed the first case of state selected ground electronic state intramolecular conformational interconversion in an isolated molecule. The distribution of conformers is altered drastically by the deposition of energy. The cis/trans ratio of the laser excited molecules may also be sensitive to the laser excitation frequency. Excitation of the N=O overtones of both cis methyl nitrite and trans methyl nitrite, which are well separated in frequency, gives resolved fluorescence spectra which mimic the absorbance spectra for cis methyl nitrite and trans methyl nitrite, respectively, thereby placing a lower bound for the conformational in...
7 citations