The vibrational spectra and conformations of ethylbenzene

Infrared spectra (4000-250 cm-1) of the liquid, amorphous, crystalline solids and solutions in liquid krypton and Raman spectra (2500-20 cm-1) of the liquid as well as the amorphous and crystalline solids of ethylbenzene and its deuterated analogue-ethylbenzene-d(10) have been recorded. The spectra indicate that in the liquid and amorphous solids a small amount of a second conformer is present, whereas only one conformer remains in the crystalline phases. Assignments of the observed band wave numbers are discussed by comparison with normal mode wave numbers and IR and RS intensities calculated from ab initio 6-31G force fields and optimised geometries for both conformers for two species. All of the normal modes of conformers have been assigned.