Electronic absorption spectra of Fe 2+ ions in oxygen-based rock-forming minerals at temperatures between 297 and 600 K

Optical absorption, EPR, infrared and Raman spectral studies of clinochlore mineral

“…In addition to these, the intervalence charge transfer (Fe 2C -Fe 3C ) band is also observed. The observed optical absorption spectrum is similar to the optical absorption spectrum observed in several iron bearing minerals [23][24][25][26][27][28][29]. The spectrochemical analysis of clinochlore mineral reveals the presence of higher concentration of iron in this mineral.…”

Synthesis and Crystal Structure of the High-pressure Iron Borate β-FeB2O4

“…A detailed assignment of these spin-forbidden transitions is impossible on the basis of our data. The whole appearance of the observed spectra is, however, very similar to other spectra reported in the literature for the chromophore [ [61] and references there).…”

Reduced radiative conductivity of low spin FeO6-octahedra in FeCO3 at high pressure and temperature

“…(For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) (Taran et al, 2009;Ullrich et al, 2002;Burns, 1993;Taran and Langer, 2001). Please note that the absorption spectra before and after LH are almost identical, indicating a reversible character of the observed transformations in the heating cycle, just as expected for a temperature-induced low-to-high spin transition.…”

“…The red-shift is likely due to the thermal expansion as the energy separation between the t 2g and e g orbitals is inversely proportional to the fifth power of the metal-ligand distance (Burns, 1993). Intensity variations of CF bands with temperature reported in the literature show a less regular behavior (Shankland et al, 1979;Fukao et al, 1968;Goncharov et al, 2008;Ullrich et al, 2002Ullrich et al, , 2004Thomas et al, 2012;Taran et al, 1994), but often may be understood in terms of temperature-induced changes in the CF symmetry (Taran and Langer, 2001) lifting the Laporte selection rule, which impedes electron transfer among the same parity states (e.g. d-d transitions).…”