The translational–rotational absorption spectrum of hydrogen

Abstract

The collision-induced translational–rotational spectrum of H2 has been accurately measured in the region from about 30 to 2000 cm−1 at 195 and 297 K. A very weak feature due to the hexadecapole-induced dipole, the U0(1) line, has been detected at 195 K in the region around 1622 cm−1. These spectra can be accurately represented by a simple, semi-empirical line shape. The effect of double transitions are considered and explicit expressions for these are given. Spectral integrals proportional to the zero and first moments are determined experimentally and compared with the theoretical moments computed on the basis of quadrupole induction for several potentials. The difference between the experimental and theoretical values, in the order of 20%, is attributed to anisotropic overlap induction, but the inferred magnitude of this component is strongly dependent on the assumed potential.