VIBRATIONAL SPECTRA OF FIVE PHASES OF SOLID HI

Author Institution: Department of Chemistry, The Johns Hopkins University$^{1}$ D. F. Hornig and G. L. Hiebert, J. Chem. Phys., 27, 752 (1957). $^{2}$ D. W. Robinson, Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Pittsburgh, Pa., March, 1964, paper no. 104.The infrared spectra of solid HI and DI as well as mixtures of the two have been reinvestigated in the temperature range $4^{\circ}$ to $78^{\circ} K$. Previously unreported transitions have been found indicating two new regions of thermodynamic stability making a total of five different structures in this temperature range. Marked differences in vibrational spectra in the fundamental region are exhibited. The lowest temperature phase gives a spectrum entirely similar to those of HBr and $HCl^{1}$ in their low-temperature phases. This is consistent with the $observation^{2}$ that the far infrared spectra of HCl, HBr, and HI at $4^{\circ} K$ are analogous and that all three have the same structure at low temperature