THE VIBRATIONAL SPECTRUM, STRUCTURE, AND POTENTIAL CONSTANTS OF NITRIC ACID.
Scientific rept. no. 1,
PENNSYLVANIA STATE UNIV UNIVERSITY PARK
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The work completes a vibrational analysis of four isotopic nitric acid molecules including the N-15 and D-species. The infrared spectra have been obtained in both the vapor and solid states. The Raman spectra of anhydrous and wet HN14O3 in the liquid phase were also studied. Three new fundamentals in the solid spectrum have been identified and two vapor phase fundamentals were reassigned. The spectrum of the solid has been interpreted on the basis of a dimeric model. Hot bands of the torsional mode in the vapor phase were resolved, and from them a barrier to hydrogen internal rotation was calculated to be 7.830.05 kcalmole. Force constants were determined which adequately describe the spectra and verify the new assignments. The frequency of the NO2 band is considerably higher than has been observed previously in other molecules containing the NO2 group. Substantial mixing is evident among the normal coordinates identified with the NO symmetric stretch, the NO2 bend, and the HON bend. Author