Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10564488 | Vibrational Spectroscopy | 2005 | 7 Pages |
Abstract
The vapors of NbF5 and TaF5 have been investigated by Raman spectroscopy in the temperature range 475-675 K and at total pressures from â¼0.1 to â¼4.0 atm. The temperature and pressure dependence of the spectra is indicative of equilibrium shifts between monomer and associated (polymer) gaseous species. The intensities of Raman bands, which were characteristic of the various species present, were exploited in order to establish the stoichiometry and thermodynamic functions of the reaction nMF5(g) â MnF5n(g) (M = Nb, Ta). It was found that unambiguously n = 2 in the studied temperature range, which implied that the predominant vapor species are monomers MF5(g) and dimers M2F10(g). The thermodynamic functions according to the studied dimerization reactions were measured from the Raman data as: (a) ÎHR = â104.3 ± 2.4 kJ molâ1, ÎSR = â175 ± 20 J molâ1 Kâ1 for 2NbF5(g) â Nb2F10(g); (b) ÎHR = â101.1 ± 3.7 kJ molâ1, ÎSR = â150 ± 30 J molâ1 Kâ1 for 2TaF5(g) â Ta2F10(g).
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
S. Boghosian, E.A. Pavlatou, G.N. Papatheodorou,