
#1
Jul311, 08:53 AM

P: 110

hi,
I am trying to figure out how does the Ti4+ Fe2+ charge transfer complex produces the blue color of sapphire quantitavily... as it is given here: http://www.webexhibits.org/causesofcolor/8.html How is it possible to calculate that this particular charge transfer requires absorption of "yellow light (~2eV)" giving rise to the complementary blue color, using very simple quantum physics because I am no expert ??? Is it possible to use bohr model and simple electromagnetism??? I will highly appreciate your contributions. 



#2
Jul811, 08:21 PM

P: 402

[1] The most commonly applied method for calculating excitation spectra, (linearresponse) time dependent DFT, is not applicable to charge transfer excitations. 



#4
Jul911, 03:46 AM

P: 82

HOW TO CALCULATE THE RESULTS OF Fe2+ Ti4+ CHARGE TRANSFER COMPLEX IN SAPPHIREThe principle is easy to understand, the detailed calculations are beyond reach. The principle is the same as in organic dyes : an electron can delocalize with oscillation between two distant and prefered zones of the molecule or the crystal. So the frequency of the oscillation is in the range of humanseeable band, and this electron can absorb several quanta at this frequency and thermalize them by mechanical means towards the lattice and its phonons, before reemitting a photon by optical way. Colour is a property of the human system of sight (human retina, human wiring of the retina, human visual cortex), not of the light or the objects under light. 



#5
Jul911, 02:05 PM

P: 110

Actually I am a student of material science & I have been encountering such phenamena recently... I am intrigued to know; what are the commonly applied methods for calculating excitation spectra??? 



#6
Jul911, 02:06 PM

P: 110

Is it possible to use QED in this case???? 



#7
Jul911, 02:10 PM

P: 110

The hope diamond has a band gap of 0.4 eV due to Boron doped in its structure... How can the 0.4eV can give rise to blue diamond!!!!!! just cant get this????!!!! 


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