Raman and infrared spectra of the 1 band of oxirane

Fourier transform spectra of oxirane [ethylene oxide (c-C2H4O)] have been recorded in the 3.17m-3.50m region with a resolution of 0.005cm(- 1). In addition, a Raman spectrum covering the same spectral region was recorded at a resolution of 0.44cm(- 1). Using the Raman spectrum, it was possible to determine the band centre of the (1) band to within 0.5cm(- 1). This determination was essential to assign the infrared region transitions of the B-type (1) band since this weak band is masked by the much stronger A-type bands (2) + (10) and (9) and (13) C-type band. Using a Watson-type Hamiltonian for an asymmetric-top molecule, it was possible to reproduce the observed energy levels to within 2 x 10(- 3) cm(- 1) and the Raman spectrum could be satisfactorily modelled. The band centre was determined to be (0) ((1)) = 3018.3454(10) cm(- 1) (1 sigma uncertainty).