Abstract

Historically, centuries ago fine precipitates of noble metals (gold, silver, and copper) were used in tinted glasses to produce beautiful colors of windowpanes used for decorations and in Lycurgus cups (developed in the fourth century AD by Roman glass workers; visit http://www.bmimages.com for the images). The first insight into the beautiful colors of stained glasses was provided by Michael Faraday in 1857, and he concluded thus: “I think that in all these cases the ruby tint is due simply to the presence of diffused finely-divided gold” (Faraday 1857). In 1908, about 50 years later, Gustav Mie theoretically explained the appearance of the striking colors as due to the resonant absorption of light in these fine metal particles (Mie 1908). This resonant absorption of light, which arises from the collective oscillations of the conduction electrons in metal nanoparticles, is being described as localized surface-plasmon resonance (SPR) in the current literature (Kreibig and Vollmer 1995, Quinten 2011). Plasmons are defined as quanta of collective oscillations of conduction electrons in metal nanoparticles vis-à-vis metal nanostructures (Ghosh and Pal 2007) and also in doped semiconductors (Luther et al. 2011). In this chapter, we discuss the interesting features of the optical responses of various metal nanoparticles and metal-semiconductor hybrid nanostructures in detail.