The overlapping hydrogen fluoride monomer-dimer spectra

Abstract

It is shown that the data of Kuipers on the absorption of the HF monomer lines can be interpreted if the line contour is expressed in a modified Lorentz form α=α 0a 2p 2[(v−v 0) 1.8+a 2p 2] −1 The apparent absorbance at the line centers has been measured under such circumstances that the temperature variation of α 0 a 2 can be obtained. It is shown that the line breadth parameter, a, has the temperature variation expected if resonant dipole intermolecular forces are for the most part responsible for the line breadth. The absorption computed from the modified Lorentz expression between the monomer lines is sometimes considerably less than the absorption that is measured. The difference is attributed to HF dimer. There result three dimer bands. The strongest is broad and featureless with a peak near 3857 cm −1, the two other bands have PQR structures with Q branch peaks at 3895 and 3965 cm −1. The temperature dependence of the dimer absorption indicates a heat of decomposition of about 6 kcal/mole.