| Affiliation: | Institute of Chemistry, Faculty of Science, Sts. Cyril and Methodius University, Arhimedova 5, P.O. Box 162, 1000, Skopje, Macedonia |
| Abstract: | The IR polarized spectra of gypsum CaSO4·2H2O were recorded at incidence angles of approximately 10 and 16 degrees. Band singlet or doublet was observed for the higher frequency ν3(SO42−) mode of Bu symmetry type, depending on polarization (n or p). A doublet was observed for the lower frequency ν3(SO42−) mode of Bu symmetry type too, irrespectively of the type of polarization. In order to give an explanation for the doublets origin, a model permittivity function was constructed. Quite good agreement exists between the reflectance based on the model permittivity function and the experimentally measured one for the high-frequency doublet. The origin of the lower frequency doublet could not be explained in this way, but may be speculated to result from an Evans type interaction between a combination of a water libration and ν2(SO42−), with the lower frequency ν3(SO42−) mode. |
