Kai-Erik PEIPONEN,¹ Martti O. A. MÄKINEN,¹ Jarkko J. SAARINEN¹ and Toshimitsu ASAKURA²

¹Department of Physics, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland, ²Faculty of Engineering, Hokkai-Gakuen University, Minami-26, Nishi-11, Chuo-ku, Sapporo, Hokkaido, 064-0926 Japan

(Received September 20, 2000; Accepted November 27, 2000)

Kramers-Kronig relations and sum rules for effective linear permittivity of the Maxwell Garnett liquid-nanosphere system were obtained using complex analysis and general expression of the effective permittivity. When reflectance from optically linear and nonlinear Maxwell Garnett nanoparticles was calculated it was observed that the reflectance, in the case of attenuated total reflection, depends on the fill fraction of the nanospheres and their nonlinear susceptibility. According to simulations a good sensitivity of the nonlinear contribution on the reflectance can be obtained by using a probe wavelength corresponding to the resonance frequency of the nanosphere system. In Kretchmann's configuration it was observed that the surface-plasmon-resonance angle depends on the fill fraction and on the intensity of the incident light. By using reflectance, it is possible to detect optically nonlinear nanospheres in liquids.

Key words : dispersion, nanoparticles, reflectance

kai.peiponen@joensuu.fi