Optical Response of Gold-Nanoparticle-Amplified Surface Plasmon Resonance Spectroscopy

• Published in: Journal of physical chemistry. C Vol. 114; no. 11; pp. 4816 - 4824
• Main Authors: Uchiho, Yuichi, Shimojo, Masayuki, Furuya, Kazuo, Kajikawa, Kotaro
• Format: Journal Article
• Language: English
• Published: American Chemical Society 25.03.2010
• Subjects: C: Nanops and Nanostructures
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp910438q

A simple formalism that predicts optical constants of a two-dimensionally distributed nanoparticle (NP) thin film is presented for analysis of the NP-amplified surface plasmon resonance. The dielectric constant of the NP thin film can be evaluated with simple expressions at low coverages (σ < 0.08), whereas the local fields induced by surrounding polarizations of NPs should be taken into account at coverages of σ > 0.08. Analytical and numerical calculations are carried out for evaluating the local fields at different conditions. The Clausius−Mossoti relation, which is usually used for evaluation of dielectric constants of a binary medium, does not hold in the NP thin films, because of the large interparticle distance and/or the retardation effect. We carried out SPR measurements for NP films with different NP coverages, and the results support the proposed analytical formalism. Finally we propose a procedure to evaluate the NP coverage from the NP-SPR profile experimentally obtained.