Why the surface plasmon always use gold or silver as a metal film?

[Poseidonho]

I found a lot the the surface plasmon on prism geometry are using gold for metal film, and part of it are using silver. Why we need use gold or sivler as a metal film, is it about the condutivity?

 

[Aeroslicer821]

I believe it has to do with the dielectric properties of the interface between gold/silver and air. Also, keep in mind that gold/silver is only used for visible light frequencies.

 

[DrDu]

The plasma frequency for surface plasmons is 1/sqrt(2) smaller than the bulk plasma frequency.
In the case of gold and silver that's in the visible. Gold surfaces also don't have an oxide layer which may change the optical properties.

 

[Poseidonho]

thanks alot:!)