Europhys. Lett.
Volume 67, Number 4, August 2004
Page(s) 614 - 619
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 August 2004
Europhys. Lett., 67 (4), pp. 614-619 (2004)
DOI: 10.1209/epl/i2003-10302-1

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

K. F. MacDonald1, V. A. Fedotov1, S. Pochon1, G. Stevens1, F. V. Kusmartsev2, V. I. Emel'yanov3 and N. I. Zheludev1

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 in final form 7 June 2004)

We have observed reversible structural transformations, induced by optical excitation at 1.55 $\un{\mu m}$, between the $\beta$, $\gamma$ and liquid phases of gallium in self-assembled gallium nanoparticles, with a narrow size distribution around 50 $\un{nm}$, 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.

64.70.Nd - Structural transitions in nanoscale materials.
78.67.Bf - Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures: Nanocrystals and nanoparticles.
68.35.Rh - Solid surfaces and solid-solid interfaces: Structure and energetics: Phase transitions and critical phenomena.

© EDP Sciences 2004