Question
Asked 1 October 2024
Why is cuprorivaite fluorescence in the green color only?
Blue and green samples from an archaeological mural painting were analyzed using a Raman spectrometer.
The results showed:
1- Blue color: It appeared that it is Egyptian blue )(cuprorivaite )
2- Green color: It is mixture of yellow and blue color, where appeared the distinctive bands of the Orpiment, but the blue color it with a background fluorescence (it is believed to be Egyptian blue (cuprorivaite ) according to the results of the SEM-EDX)..
Similar questions and discussions
What are the electronic processes that survive in the bulk of an insulator?
Pedro L. Contreras E.
Insulators can be defined as those materials where thermal conduction drived by phonons is the main physical process, and any kind of electronic processes can be neglected.
Other researchers use a model elaborated using the framework of bands, which is a useful theoretical model, i.e., the existence of a gap between the conduction and valence bands with a width > 3.0 eV defines an insulator.
For students, insulators can be defined using the interactive PhET simulation "Conductivity" as plastics where an applied voltage or a light shined on them, does not move the electronic degrees of freedom.
More elaborated models where proposed in the 60s by Profs. Mott and Ziman among others.
I am wonder if any physicist that have worked using ab initio calculations can enlighten us about insulators?
Thanks to all readers and researchers willing to participate ad to follow this RG thread.
References:
1. N. F. Mott, Electrons in disordered structures, Advances in Physics, Vol 16(41,49), 1967.
2. J. M. Ziman, Phil. Mag. Vol 6, 1961.
3. PhET Interactive Simulations, University of Colorado Boulder, licensed under CC-BY-4.0 (https://phet.colorado.edu).
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