I am currently trying to find some resources that discuss the temperature dependence of interband transitions in metals, and how this affects the reflectivity of the metal as a function of temperature at visible/UV wavelengths. It is well known that the reflectivity of metals decreases at IR frequencies with increasing temperature due to the increased damping of free-electron oscillations. However, I am struggling to find anything significant discussing how temperature affects the interband transitions within a material and thus reflectivity of a metal at high frequencies of light.
I can imagine that soume temperature dependence would be present due to the broadening of the Fermi Dirac distribution, but most resources I have seen simply dismiss the temperature dependence of the interband transitions to be too small to be significant.
If anyone knows of any good resources that discuss this, it would be greatly appreciated.
Thank you in advance.