Optical characterization and manipulation of alkali metal nanoparticles in porous silica

• Published in: The European physical journal. D, Atomic, molecular, and optical physics Vol. 49; no. 2; pp. 201 - 210
• Main Authors: Burchianti, A., Bogi, A., Marinelli, C., Maibohm, C., Mariotti, E., Sanguinetti, S., Moi, L.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.09.2008; Springer; Società italiana di fisica; EDP sciences
• Subjects: Applications of Nonlinear Dynamics and Chaos Theory; Atomic; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Molecular; Nanocrystals and nanoparticles; Optical and Plasma Physics; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physical Chemistry; Physics; Physics and Astronomy; Quantum Information Technology; Quantum Physics; Spectroscopy/Spectrometry; Spintronics; 78.67.Bf Nanocrystals and nanoparticles; 64.70.Nd Structural transitions in nanoscale materials; 68.43.Tj Photon stimulated desorption; Cluster size; Porous materials; Alkali metals; Cesium; Metal clusters; Rubidium; Transmittance; Silica; Nanoparticles; Optical measurement; Optical properties; Nanostructured materials; Optical absorption
• ISSN: 1434-6060; 1434-6079
• DOI: 10.1140/epjd/e2008-00164-5

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.