A normal coordinate analysis of B-dimorphite

Abstract

Infrared and Raman spectra are reported for α dimorphite and the fundamental vibrations assigned. Using this data, together with Whitfield's earlier crystallographic work a force field has been evaluated for the two symmetry species; the E species being characterised with more certainty than the A1 species. The data has also been used to calculate tentative thermodynamic values for As4.S3. To Provide some check on method and results, comparison was made with analogous seven atom C3v compounds; P4 S3 and P4.Se3. Until further isotopic data and polarisation data are available more progress in this type of analysis for α dimorphite will be difficult.