화학공학소재연구정보센터
Journal of Physical Chemistry, Vol.100, No.50, 19273-19279, 1996
CH Stretching Overtone Investigation of Relative CH Bond Lengths in Pyridine
We have recorded the room temperature CH stretching overtone spectra of pyridine, both in the vapor and in the liquid phase. We have used intracavity laser photoacoustic as well as conventional near-infrared absorption spectroscopy to measure these overtone transitions. Peaks corresponding to three nonequivalent CH stretching local modes are assigned in the high-energy vapor phase spectrum, as opposed to previous investigations which assigned only two. Absolute oscillator strengths are obtained from the conventional spectra and relative oscillator strengths between the observed peaks within a given overtone from the photoacoustic spectra. Oscillator strengths are calculated with an anharmonic oscillator local mode model and ab initio dipole moment functions. In the high-energy vapor phase spectrum, we have assigned the three peaks based on comparisons with ab initio calculated bond lengths and accurate overtone intensity calculations. Our simple calculations, which contain no adjustable parameters, are in very good agreement with both the absolute and relative observed intensities.