POLARIZED VACUUM UV SPECTRA OF CRYSTALLINE UREA
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Date
1989
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Ohio State University
Abstract
Polarized reflection spectra of single crystals of urea and a urea-hexadecane adduct have [FIGURE] been measured to 135 nm. Absorption spectra obtained by Kramers-Kronig analysis of the reflection data indicate the presence of three strong bands at $56,000 cm^{-1}. 62,000 cm^{-1}$ and $65,000 cm^{-1}$ The transition moment directions are unambiguously found to be y, z and y and correspond to transitions with excited state symmetries of $B_{2}, A_{1}$ and $B_{2}$, respectively. In spite of the fact that urea is a fairly small molecule of reasonably high symmetry and is closely related to the heavily studied amide grouping, little previous work on urea has been found. The only prior report of its electronic spectrum showed a single broad band centered at $58,800 cm^{-1}$, while the predictions of an extensive ab-initio calculation of the electronic states published in 1974 are completely inadequate.
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Author Institution: Rocketdync Division, Rockwell International Corp., 6633; Department of Chemistry, University of California at San Diego