Does it depends on the flatness and pureness of surface. does it change when dust or oxides settle on it.

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    $\begingroup$ That is two times a yes. Could you be - much - more specific? $\endgroup$ – my2cts Jun 15 '18 at 9:15
  • $\begingroup$ does transmittance increase when the metal is not totally pure?.Why they only reflect but not refract?,reflection and refraction are same process but vary in direction right?.can we manipulate the wave to increase refraction or it depends only on the metal $\endgroup$ – Anns Jun 15 '18 at 9:19

Relectivity depends is primarily a surface phenomena; it depends upon surface roughness (as it roughens, scattering increases), the purity (surface impurities change the fundamental physical constants), and crystal structure (111 has different properties than 110 crystal orientation for most crystals).

If an oxide has formed, as with aluminum, reflectivity decreases rapidly. This is because aluminum oxide is an insulator, and not a metal, and the natural formation of the oxide results in a roughened surface.

Note that as metals are very strong absorbers of most wavelengths, you will see neither refraction nor transmission unless the metal is very, very thin, typically a few nanometers.

  • $\begingroup$ If aluminium is strong absorber of almost all wavelength,what happens when very high intense infrared beam incidents on it,will it dissociate or vibrational resonance matters? $\endgroup$ – Anns Jun 15 '18 at 14:27
  • $\begingroup$ As the energy density increases, the material will photo-dissociate. I have cut glass, ceramics, and metals with a 1 watt average power beam of ultrafast 800 nm pulses, tightly focused. One of the new hazards is reflection from the plasma surface! $\endgroup$ – Peter Diehr Jun 15 '18 at 18:14
  • $\begingroup$ Can you answer my other question link.also dissociation frequency independent right?.thank you. $\endgroup$ – Anns Jun 15 '18 at 18:27
  • $\begingroup$ So dissociation is frequency independent right?.Please reply. $\endgroup$ – Anns Jun 16 '18 at 4:45
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    $\begingroup$ @anns: if you apply enough power, in a small enough space, the linear regime is overwhelmed by multi-photon capture, which acts just like the higher frequency multiple. This can be observed with ultrafast laser pulses. $\endgroup$ – Peter Diehr Jun 16 '18 at 13:21

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