Controlling the coexistence of structural phases and the optical properties of gallium nanoparticles with optical excitation

¹ School of Physics and Astronomy, University of Southampton Highfield, Southampton, SO17 1BJ, UK
² Department of Physics, Loughborough University - Loughborough, LE11 3TU, UK
³ Department of Physics and International Laser Centre, Moscow State University Vorobievy Gori, 119899 Moscow, Russia

Received: 8 December 2003
Accepted: 7 June 2004

Abstract

We have observed reversible structural transformations, induced by optical excitation at 1.55, between the β, γ and liquid phases of gallium in self-assembled gallium nanoparticles, with a narrow size distribution around 50, on the tip of an optical fiber. Only a few tens of nanowatts of optical excitation per particle are required to control the transformations, which take the form of a dynamic phase coexistence and are accompanied by substantial changes in the optical properties of the nanoparticle film. The time needed to achieve phase equilibrium is in the microsecond range, and increases sharply near the transition temperatures.