# HOT BANDS IN OVERTONE ABSORPTION TRANSITIONS: HIGH TEMPERATURE PHOTOACOUSTIC SPECTRA

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 dc.creator Hassoon, S. en_US dc.creator Snavely, D. L. en_US dc.date.accessioned 2006-06-15T18:50:53Z dc.date.available 2006-06-15T18:50:53Z dc.date.issued 1993 en_US dc.identifier 1993-RB-10 en_US dc.identifier.uri http://hdl.handle.net/1811/18506 dc.description Author Institution: Center for Photochemical Sciences, Bowling Green State University en_US dc.description.abstract Vibrational overtone hot band spectra are presented. The laser photoacoustic spectra of the $4\nu_{N-H}$ and $4\nu_{C-H}$ overtones of pyrrole, the $5\nu_{C-H}$ of methyl isocyanide and acetonitrile. the $5\nu_{C-H}$ and $6\nu_{C-H}$ of isobutane, and the $6\nu_{C-H}$ of cyclohexane were measured at temperatures up to 140C and compared to the room temperature spectra. Hot bands were identified by their temperature dependence. We observed hot bands in pyrrole, methyl isocyanide and isobutane. From the relative intensities of the hot bands to the main band, the wavenumbers of the thermally populated states were $405 \pm 100, 410 \pm 100$ and $208\pm 100 cm^{-1}$ for pyrrole, isobutane and methyl isocyanide, respectively. These values compare well to the bending motion frequencies in these molecules. A large red shift of the hot bands from the main peak was observed, as expected for high overtone transitions due to the large anharmonicity. The anharmonic constants determined from these shifts are $25cm^{-1}$ for the N-H in pyrrole and $20 cm^{-1}$ for the $C-H$ in methyl isocyanide and cyclohexane. In the case of the $N-H$ absorption the hot band was completely separated from the main transition. In the $C-H$ overtone spectra these hot band absorptions were not separated and result in an apparent increased width of the overtone transition. en_US dc.format.extent 87214 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title HOT BANDS IN OVERTONE ABSORPTION TRANSITIONS: HIGH TEMPERATURE PHOTOACOUSTIC SPECTRA en_US dc.type article en_US