Related: Why did high quality mirrors use aluminum coatings instead of silver?

After reading Chris White’s and LDC3’s comments in the above related link, it got me wondering about silver’s atomic structure. When looking at the reflectance vs. wavelength plot below,

enter image description here

silver has a particularly strong resonance slightly around 315 nm when compared to the other metals. I believe that I have good understanding what silver is doing at optical frequencies (see this previous post) but I have no idea why there is such a strong UV absorption around 315 nm in silver. Can someone explain what is going on?


The resonances are due mainly to plasma oscillations. But these metals are not simple plasmas; there are interband transitions as well as collective plasma oscillations, and the frequencies of these various excitations can overlap causing interactions. In silver, there is no interband transitions at the plasm frequency, so the plasma resonance is not damped, whereas in other metal, that is not the case. Even in silver interband transitions play a role in shifting and sharpening the resonance.

  • $\begingroup$ thanks Gary, I needed to read up on interband transitions and I think I grasp what you are saying. I have a lot to learn still and thanks for giving me the right direction. $\endgroup$ – Carlos Jun 4 '14 at 11:46

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