Vibrational analysis of urea

The vibrational spectrum of urea was interpreted by measuring the solid state infrared spectra of eight isotopomers of urea at room temperature and at -196 degrees C., and Raman spectra at room temperature and at -120 degrees C, and of a urea-water solution. Force field computations on isolated urea and on urea in its crystal structure, at the Hartree-Fock level with a 6-21++G** basis set, were also employed. High-pressure measurements utilizing a diamond anvil cell were observed not to be useful.