Jet-cooled infrared spectra of the formic acid dimer by cavity ring-down spectroscopy: observation of the OH stretching region Original Research Article

Jet-cooled infrared spectra of the formic acid dimer (HCOOH)2 and its isotopomers (DCOOH)2 and (HCOOD)2 were measured by cavity ring-down spectroscopy in the region of 2800–3300 cm−1. The `cold bandʹ spectra showed resolved vibrational peaks which are not observed at room temperature while broad structure in the OH stretching region persists, indicating that the broad structure is inherent in the molecular complexes. From analysis of the vibrational structure, most of the sharp peaks were assigned to binary combinations. The broad structure was interpreted as the result of intensity borrowing from the OH stretching level to the manifold of combination/overtone levels, and the assignment of the OH stretching band was presented.