Dear MEEP users, I am trying to model the Multilayered nanoshell, which contains a metal core, a dielectric silica and the outer metal shell. At 1st, i divide this complex structure into several parts and calculate its extinction efficiency. I know from the litrature that if you enclose a silica sphere inside a metal shell (single layer nanoshell) then the extinction peaks would be red shifted. But when i tried to enclose a metal inside a silica shell then i also obtained a red shifted peak. Can somebody tell me the role of the silica in this structure. I mean why the extinction peak is always red shifted. I have attached a figure with the email, which shows the extinction efficiency of a single silver sphere and a gold sphere and then enclosing them in a dielectric silica due to which the extinction peaks red shifted. However, incase of enclosing the silica inside a metal, we get a larger red shift. But my question is, why incase of enclosing a metal inside a silica we get a red shift? Thanks. BR, Jack
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