Rotational analysis of the 2ν₅ band of formaldehyde

Abstract

The spectrum of the 2ν₅ C–H stretching band of formaldehyde was measured by Barry et al. (Phys. Chem. Chem. Phys. 4, 445 (2002)) with FTIR spectroscopy. In the current work, this spectrum has been rotationally analysed with the help of PGOPHER, a general purpose program for simulating and fitting rotational spectra. The spectrum shows several perturbations and there is sufficient information available on the vibrational structure from a dispersed fluorescence spectra study by Bowens et al. (J. Chem. Phys. 104, 460 (1996)) and theoretical calculations by Burleigh et al. (J. Chem. Phys. 104, 480 (1996)) to allow the perturbing states to be identified and deperturb the energy levels. The resulting perturbation parameters and rotational constants enable the experimental line positions to be reproduced with an average error of 0.013 cm⁻¹. Also presented is a list of line positions and relative intensities in the region around 1.76 µm.