CONDON MODULATION SPECTROSCOPY OF SOLID HYDROGEN

1. E.U. Condon. Phys. Rev., 41 759 (1932) 2. K. E. Kerr, T. Momose, C. M. Gabrys, D. P. Weliky, and T. Oka. 48th International Symposium on Molecular Spectroscopy Columbus, Ohio June 1993. Paper RE08 3. K. E. Kerr, T. Momose D. P. Weliky, C. M. Gabrys, and T. Oka. Phys. Rev. Lett. Submitted.Author Institution: Department of Chemistry and Department of Astronomy and Astrophysics, The University of Chicago; Department of Chemistry, Faculty of Science Kyoto UniversityThe Condon $effect^{1}$, in which an electric field induces otherwise forbidden transitions, has recently been used to induce and modulate the $Q_{1}(0)$ vibrational fundamental of solid $parahydrogen.^{2,3}$ Condon modulation has resulted in a two order of magnitude improvement in the sensitivity of solid hydrogen spectroscopy and has allowed the observation of Raman type transitions in the infrared. The linewidth and line position of the field induced $Q_{1}(0)$ transition has been studied as a function of temperature and orthohydrogen concentration. The line shift has been explained as resulting from the temperature variation of the molar volume and thus the intermolecular distances. The enhanced sensitivity of Condon modulation has been in the exploited in the observation of the $Q_{3}(0)$ overtone of parahydrogen and has been applied to the $Q_{1}(0)$ and $Q_{1}(1)$ transitions of deuterium impurities in parahydrogen. Several of the features in the field modulated $Q_{1}(0) D_{2}$ impurity spectrum which are induced by the much larger quadrupolar fields of $J=1$ orthohydrogen and paradcuterium appear to be Stark Shifted