کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1408064 | 1501904 | 2007 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Vapor complexation in the CsI-HoI3 system up to 1300 K and the f â f hypersensitive transition intensities of Ho(III) in different coordination geometries
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Electronic absorption spectroscopy is used in the temperature range 850-1300 K, to study the vapor species over molten HoI3-CsI (1:1), molten CsI and solid HoI3. Quantitative absorbance measurements are used to calculate the following enthalpies of transition: ÎHsubl(HoI3) = 271 ± 3 kJ molâ1, ÎHvap. (CsHoI4) = 155 ± 2 kJ molâ1 and ÎHvap. (CsI) = 151 ± 2 kJ molâ1. The ligand field components of the 5G6 â 5I8 hypersensitive transition of Ho(III) for the three different, all iodide, coordination geometries of HoI3(g), CsHoI4(g) and HoI63â (in molten CsI) have been examined in detail. The molar absorptivities (ε) and oscillator strengths (f) increase as the coordination decreases from the “octahedral” HoI63â (ε = 65 L molâ1 cmâ1; f = 99 Ã 10â6) to the distorted tetrahedral HoI4â (ε = 235 L molâ1 cmâ1; f = 290 Ã 10â6) to the trigonal HoI3 (ε = 390 L molâ1 cmâ1; f = 500 Ã 10â6). The main factors affecting the hypersensitive transition intensities are the coordination number and symmetry and the ligand polarizability as well as the Boltzmann population effects on the ground state levels which are responsible for the appearance of “hot” bands in the spectra. A C2v symmetry is anticipated for the CsHoI4(g) with the HoI4â “tetrahedra” distorted towards a square planar symmetry leading to a structure with a pseudo-like inversion center.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure - Volume 832, Issues 1â3, 30 April 2007, Pages 38-47
Journal: Journal of Molecular Structure - Volume 832, Issues 1â3, 30 April 2007, Pages 38-47
نویسندگان
G.N. Papatheodorou, A. Chrissanthopoulos,