What is the bulk plasmon peak?

[macabre]

When I read “Extraordinary optical transmission through sub-wavelength hole arrays”, I saw this figure but I don't get the bulk plasmon peak at 326 nm. What is the mean of bulk plasmon peak?

 

[plasmon_shmasmon]

View attachment 236171
When I read “Extraordinary optical transmission through sub-wavelength hole arrays”, I saw this figure but I don't get the bulk plasmon peak at 326 nm. What is the mean of bulk plasmon peak?

A plasmon is a collective oscillation of free electrons, occurring in metals and metal-like materials. There are different types of plasmons. Bulk plasmons are collective oscillations of the "bulk" 3D electron gas...that is, the electrons in the material that do not "sense" the surface. Then there are surface plasmons which exist only at the interfaces of a material (think waves on the surface of a pool).

The plasmonic behavior of metals is what makes them highly reflective below the plasma frequency (think visible light, IR, and above). Above the plasma frequency (which is effectively UV for most materials), metals are transparent.

Indeed, in the case above, the bulk plasmon wavelength is in the UV, as expected.

[BTW, I was born to answer this. See username.]

 

[macabre]

Thanks a lot.