Eur. Phys. J. D 24, 223-226 (2003)
https://doi.org/10.1140/epjd/e2003-00192-7

Influence of phase transitions on the second harmonic generation in metal nanoparticles

¹ INFM - Dip. Fisica “A. Volta" Università di Pavia, Via Bassi 6, 27100 Pavia, Italy
² INFM - Dip. Elettronica, Università di Pavia, Via Ferrata 1, 27100 Pavia, Italy
³ Laboratoire de la Physique de la Matière Condensée (URA 190) , Université de Nice Sophia Antipolis, 06108 Nice Cedex, France

Corresponding authors: ^a malvezzi@ele.unipv.it - ^b patrini@fisicavolta.unipv.it

Received: 10 September 2002
Published online: 3 July 2003

Abstract

In this work we use nonlinear optical properties of Ga nanoparticles monolayers of different average sizes embedded in dielectric matrices to investigate the liquid–solid phase transitions in these materials. Ga nanoparticles, formed by exploiting the partial wetting of liquid Ga over a SiO_x surface are irradiated with fs laser pulses from a Ti:sapphire source. The resulting Second Harmonic (SH) generated in the reflection and transmission directions is measured along the phase transitions by cooling the sample from 320 K down to liquid nitrogen temperature. Hysteresis cycles are observed in the nonlinear transmission, which exhibit a strong amplification from the solid to liquid values as compared to the linear optical results. A simple model for SH generation, based on Mie scattering calculations which includes the effect of surface plasmon resonance provides a fair key for the interpretation of the observed effects.