The Unshifted Atom-A Simpler Method of Deriving Vibrational Modes of Molecular Symmetries

EMR Kiremire

Department of Chemistry, University of Namibia, Private Bag 13301,Windhoek(Namibia)

ABSTRACT:

The infrared and Raman spectroscopy are widely utilized to study molecular structures. Of great interest is the great interest is the striking correlation between the molecular geometry and the infrared and Raman spectra of simple molecules and ions. This incredible correlation tends to be shadowed by deep theoretical and mathematical principles such that a good number of scholars are denied the joy of appreciating the correlation between molecular symmetry and infrared and Raman spectra. The ‘unshifted atom’ method presents a highly simplified approach based on basic knowledge of symmetry elements and the effect  of symmetry operations on molecular geometries to determine the number of unshifted atoms (USa). Inserting the Cartesian coordinates(X,Y,Z) on an unshifted atom and applying symmetry operations, the contributions to the character (XSO) by the symmetry operations are obtained. A simple multiplication of the numbers of unshifted atoms (USa) in a point group with the corresponding numbers of (XSO) generates a REDUCIBLE REPRESENTATION from which the VIBRATIONAL MODES of a molecule/ion are deduced. Examples of different molecular geometries have been presented to illustrate the simplicity, flexibility and viability of the method.

KEYWORDS:

Vibrational modes; Molecular symmetries; Spectroscopy

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Copy the following to cite this article: Kiremire E. The Unshifted Atom-A Simpler Method of Deriving Vibrational Modes of Molecular Symmetries. Orient J Chem 2012;28(1).

Copy the following to cite this URL: Kiremire E. The Unshifted Atom-A Simpler Method of Deriving Vibrational Modes of Molecular Symmetries. Orient J Chem 2012;28(1). Available from: http://www.orientjchem.org/?p=23785