کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1235544 | 968849 | 2007 | 7 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Isosbestic-like point in the polarized reflectance spectra of monoclinic crystals—A quantitative approach Isosbestic-like point in the polarized reflectance spectra of monoclinic crystals—A quantitative approach](/preview/png/1235544.png)
If two overlapping bands originate from transition moments that are perpendicular and lie along the principal axes of the infinity frequency dielectric tensor, an isosbestic-like point (ILP) appears in the overlaid polarized IR reflectance spectra of single crystals. These conditions can also be met in principle in case of the reflectance from the ac-plane of a monoclinic crystal despite of the crystal's low symmetry. In order to determine the transition moment directions, diagonalization of the infinity frequency dielectric tensor should be performed. It is shown that a critical magnitude for the appearance of ILP is the angle of incidence. An increase of this angle leads to a transformation of the ILP to an isosbestic-like region, which eventually vanishes at higher incidence angles. Polarized reflectance spectra of gypsum (CaSO4·2H2O), recorded from the ac crystal face, were used to verify the theoretical results.
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 68, Issue 3, November 2007, Pages 632–638