HOW TO CALCULATE THE RESULTS OF Fe2+ Ti4+ CHARGE TRANSFER COMPLEX IN SAPPHIRE


by Panthera Leo
Tags: charge, complex, results, sapphire, transfer
Panthera Leo
Panthera Leo is offline
#1
Jul3-11, 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.
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cgk
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#2
Jul8-11, 08:21 PM
P: 402
Quote Quote by Panthera Leo View Post
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 ???
That is not possible. Experts at computational chemistry for solids may be able to do this calculation, using lots of hardcore many-body physics and big computers, but even they would need to pull tricks[1]. And I still wouldn't bet on them being able to get quantitative agreement, let alone predictions. Using simple methods and not being an expert, I'm afraid you have no chance.

[1] The most commonly applied method for calculating excitation spectra, (linear-response) time dependent DFT, is not applicable to charge transfer excitations.
Drakkith
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#3
Jul8-11, 08:58 PM
PF Gold
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P: 11,030
Holy capslock Feynman.

Jacques_L
Jacques_L is offline
#4
Jul9-11, 03:46 AM
P: 82

HOW TO CALCULATE THE RESULTS OF Fe2+ Ti4+ CHARGE TRANSFER COMPLEX IN SAPPHIRE


Quote Quote by Panthera Leo View Post
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???
Thank you for the reference to this paper. It is very clear and I long needed it.
The 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 human-seeable 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.
Panthera Leo
Panthera Leo is offline
#5
Jul9-11, 02:05 PM
P: 110
Quote Quote by cgk View Post
That is not possible. Experts at computational chemistry for solids may be able to do this calculation, using lots of hardcore many-body physics and big computers, but even they would need to pull tricks[1]. And I still wouldn't bet on them being able to get quantitative agreement, let alone predictions. Using simple methods and not being an expert, I'm afraid you have no chance.

[1] The most commonly applied method for calculating excitation spectra, (linear-response) time dependent DFT, is not applicable to charge transfer excitations.
I am trully stunned!!!!!

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???
Panthera Leo
Panthera Leo is offline
#6
Jul9-11, 02:06 PM
P: 110
Quote Quote by Drakkith View Post
Holy capslock Feynman.
You reminded me of QED :)

Is it possible to use QED in this case????
Panthera Leo
Panthera Leo is offline
#7
Jul9-11, 02:10 PM
P: 110
Quote Quote by Jacques_L View Post
Thank you for the reference to this paper. It is very clear and I long needed it.
The 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 human-seeable 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.
Color is undoubtedly a magnificant phenamena to study from the scientific perspective... A combination of physics, chemistry, biology & so on ....

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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