高屈折率プリズム／中間屈折率層／金属薄膜系における赤外吸収増大の研究

Abstract

An IR absorption enhancement is investigated as a function of the evaporated gold film thickness in an ATR prism configuration (the Hybrid configuration) intermediate be-tween the Otto's and the Kretschmann's. When the metal film is very thin and has an island structure, the IR enhancement is caused by the collective electron resonance. When the metal film is sufficiently thick, the enhancement arises from the optical cavity effect. These results support the enhancement mechanisms previously proposed by us in both the Otto and Kretschmann configuration independently. Our experiments also reveal the pres-ence of a transition thickness region between the island and the continuous films.