Vibrational Spectroscopy of the CCl4 v1 Mode: Theoretical Prediction of Isotopic Effects

James D. Gaynor
Anna M. Wetterer
Rea M. Cochran
Edward J. Valente, University of Portland
Steven G. Mayer, University of Portland

Journal of Chemical Education, 2015, Volume 9, Issue 6, 1081-1085.

© 2015 The American Chemical Society and Division of Chemical Education, Inc.

Linked version is final published version.

Abstract

Raman spectroscopy is a powerful experimental technique, yet it is often missing from the undergraduate physical chemistry laboratory curriculum. Tetrachloromethane (CCl4) is the ideal molecule for an introductory vibrational spectroscopy experiment and the symmetric stretch vibration contains fine structure due to isotopic variations of the molecule according to C35Clx37Cl4–x. We report simple theoretical predictions of the fine structure, calculation of Raman differential scattering cross sections, and discussion of the inherent asymmetry in the v1 mode resulting from the different isotopes of chlorine. All calculations and discussion are appropriate for an undergraduate physical chemistry laboratory as either an independent dry lab or a supplement to a pre-existing vibrational spectroscopy lab.