Showing papers by "Willis B. Person published in 1993"

Experimental and Ab Initio Quantum Mechanical Studies of the Vibrational Spectra of Isolated Pyrimidine Bases

Abstract: A review is presented of experimental studies of infrared and Raman spectra of thymine isolated in an argon matrix at about 12 K. The experimental techniques for study of the vibrational spectra of matrix-isolated pyrimidines are described, and the reasons for such studies are illustrated by comparison of the infrared and Raman spectra of matrix-isolated thymine with spectra in the solid phase. Comparison of the infrared spectrum of p-quinone isolated in an argon matrix with that for the molecule in the gas phase establishes that the spectra of matrix-isolated molecules are expected to be very similar to those for the gas phase, except for the lack of rotational structure in the matrix spectra. On the other hand, hydrogen bonding in the solid phase has a profound effect on the infrared spectrum, with much smaller effect on the Raman spectrum. Ab initio quantum-mechanical calculations at the HF/6–3 lG(d) level made for the isolated molecules are compared with the experimental spectra and their application to the interpretation of the latter is illustrated.