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I am dealing with some reflectance spetra of pure or mixed metal, so no ion complex usually. I have some reflectance spectra that show bands with lower reflectance thay my be linked with absorptions. I would like to understand which transition could lead to that absorption.

For istance in the case of copper in the NIST website I have found all the energies levels of the pure copper Neutral Copper ( Cu I ) (I guess that ( Cu I ) is not a Stock notation otherwise oxidation state would be 0) but I can't understand how to derive the transition from the energy level, theoretically if a energy level it at a certian energy $E_{1}$ and another level it is at another energy $E_{2}$ transition should occur when the photon has energy $\Delta E$. How can I figure out the possible $\Delta E$ where transitions may occur? What are the selection rules?

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The table shows data for atomic spectra. When you are talking about reflectance spectra I assume that you mean reflection from a solid piece of metal. If this is the case, the absorption spectrum of a metal is not given by transitions between the atomic levels of the isolated atom. You need to look at the band structure of the metal for any indication of possible absorption bands. But some absorption may be due to processes related to free electrons, like creation of plasmons (see plasma resonance in metals).

Even though the band structure of the metal can, in principle, be calculated starting from the information about individual atoms, it is not a trivial process.

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  • $\begingroup$ Thanks, so how can I look at the band structure of the metal? $\endgroup$ – G M Aug 24 '16 at 7:02
  • $\begingroup$ You could just google "Copper band structure". You will get a lot of hits. For more detailed data search the same phrase on google scholar. You will find papers discussing the band structure. For example, this one:journals.aps.org/pr/pdf/10.1103/PhysRev.129.138 $\endgroup$ – nasu Aug 24 '16 at 15:38
  • $\begingroup$ Thanks I have already that article, but I really can't figure out how to identify where in terms of wavelength the absortpion take place.... $\endgroup$ – G M Aug 25 '16 at 8:36

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