NANOPARTICLES AND NANOTUBES PRODUCED BY LASER-INDUCED DECOMPOSITION OF GAS PHASE PRECURSORS
Friedrich Huisken, Institute of Solid State Physics, Friedrich-Schiller-Universität Jena and Max
Planck Institute for Astronomy, Heidelberg, Germany
Nanoparticles of various kinds (silicon, carbon, silicon carbide, iron, etc.) are produced by
pulsed CO2-laser-induced pyrolysis of suitable precursor gases in a dedicated flow reactor. They
are extracted, directly after generation, into a high vacuum chamber, thus forming a freely propagating “molecular beam” of non-interacting nanoparticles. This beam traverses a differential
chamber and finally enters a time-of-flight mass spectrometer where in situ analysis of mass and
velocity distributions is performed. High resolution electron transmission microscopy (HRTEM)
and atomic force microscopy (AFM) are performed to characterize the morphology of deposited
nanoparticles. Due to the bright photoluminescence (PL) of nanostructured silicon that is enabled
by the quantum confinement, detailed studies were carried out regarding the optical properties of
size-selected silicon nanocrystals. When irradiated by UV light, samples containing the proper
particle size exhibit strong light emission in the red. As predicted by the quantum confinement
model, the peak of the PL curve shifts with decreasing particle size to smaller wavelengths (i.e.
higher energies). Most recent investigations are devoted to the production of luminescent Sibased nano- and microstructures as well as to the solvation of luminescent Si particles in liquid
media. Dense layers of aligned carbon nanotubes were produced by CO2-laser assisted decomposition of sensitized hydrocarbon mixtures with iron pentacarbonyl.