OH- and CH-stretching overtone spectra of catechol

We have recorded the CH-, OH-, and OD-stretching fundamental and overtone spectra of catechol (1,2-dihydroxybenzene, pyrocatechol) and selectively deuterated catechol. Conventional and intracavity photo-acoustic spectroscopy were used to record room temperature spectra of catechol in solution and in the vapor phase, whereas nonresonant ionization detected spectroscopy was used to study catechol in a supersonic jet. The spectra can be explained in terms of a local mode model with one oscillator for each of the nonequivalent CH, OH, or OD bonds. Intensities of the CH-, OH-, and OD-stretching transitions were calculated with an anharmonic oscillator local mode model and ab initio determined dipole moment functions. Our simple calculations are in good agreement with the observed intensities. Line widths in the jet-cooled spectra are discussed in terms of intramolecular vibrational redistribution. The spectroscopic and theoretical results are in agreement with a relatively weak intramolecular hydrogen bond.