Far i.r. absorption of thiophene in the liquid and plastic phases

• Published in: Spectrochimica acta. Part A: Molecular spectroscopy 1981, Vol.37 (11), p.977-980
• Main Authors: Pinan-Lucarre, J.P., Edewaard, D.C., Moeller, K.D.
• Format: Article
• Language: English
• ISSN: 0584-8539
• DOI: 10.1016/0584-8539(81)80025-6

The far i.r. absorption spectrum of thiophene C 4H 4S has been studied in the 10–200 cm −1 spectral region. Results were obtained for the liquid state at 303 and 208 K and the plastic phase at 223 K. The frequencies of the absorption peaks represent the molecular libration frequency. The widths of the peaks at half height relates to the perturbation of the librational motion in the potential wells. The experimental results are compared with the theoretical data derived from the Brot—Lassier reorientational model applied to results from the middle i.r. and Raman spectra. For furan, another heterocyclic molecule, a comparison is made of published far i.r. and microwave data with our middle i.r. and Raman data exploited by application of the theoretical model by Brot and Lassier. It is shown that the theoretical model gives a fair description of the reorientational phenomena of thiophene and furan.