Eur. Phys. J. D 49, 201-210 (2008)
https://doi.org/10.1140/epjd/e2008-00164-5

Optical characterization and manipulation of alkali metal nanoparticles in porous silica

¹ CNISM and Physics Department, University of Siena, 53100 Siena, Italy
² Mads Clausen Institute, NanoSYD, University of Southern Denmark, 6400 Sønderborg, Denmark
³ Physics Department, University of Pisa, 56127 Pisa, Italy

Corresponding author: ^a burchianti@unisi.it

Received: 5 May 2008
Published online: 22 August 2008

Abstract

Rubidium and cesium metal nanoparticles were grown in nanoporous silica samples placed in alkali vapor cells. Their size and shape were investigated by measuring the sample optical transmittance. Spectral changes due to photodesorption processes activated by weak light were also analyzed. Alkali atoms photoejected from the silica walls diffuse through and out of the nanopores, modifying both the nanoparticle distribution in the silica matrix and the atomic vapor pressure in the cell volume. The number of rubidium and cesium atoms burst out of the samples was measured as a function of photon energy and fluence. The optical absorption measurements together with the analysis of the photodesorption yield give a complete picture of the processes triggered by light inside the nanopores. We show that atomic photodesorption, upon proper choice of light frequency and intensity, induces either growth or evaporation of nanosized alkali metal clusters. Cluster size and shape are determined by the host-guest interaction.