Shape and Size Dependence of Noble Metal Nanoparticles on Decay Rates of an Emitter

Plasmonics deals with the interaction of the electromagnetic field of an emitter with the noble metal nanoparticles or nanosheets through the evanescent wave coupling. The emitter can either be excited directly by an excitation light or by the evanescent field itself. Excitation through the evanescent field works as a sensor as these fields are sensitive to the surroundings. In this work, the photoluminescence and excited state decay rate of a standard laser dye rhodamine B (RB) has been studied as a function of the shape and size of gold nanoparticles (AuNPs). It has been found that for example, for an octahedral shaped AuNP, the luminescent yield of RB is reduced by a factor of 20 in water. Finite element simulations also show that the localized field of AuNPs changes with their morphology that affects the decay rate of an emitter.