Photoluminescence from gas-suspended nanoparticles synthesized by laser ablation: A pathway to optimized nanomaterials
Laser ablation of solids into background gases is a proven cluster-assembly method. It was used to synthesize the first carbon fullerenes in 1985.(1) In this technique, a solid material is vaporized by a high-powered laser pulse to form a partially-ionized plasma containing atoms and small molecules. The hot plasma plume quickly expands to collisionless conditions unless confined by a background gas. In this case, the plume atoms become trapped together and can form clusters as small as a few atoms, or larger clusters of 1--10 nm diameter (25--26,000 atoms for silicon). However, until now very little was known of the temporal and spatial scales for nanoparticle formation in background gases, or how the nanoparticles are transported and deposited after their formation. It is often unclear whether nanoparticles found on substrates were grown in the gas phase or from nuclei formed on the substrate surface. Here, the formation and transport of silicon nanoparticles in laser ablation plumes is revealed by a comparison of Rayleigh-scattering and the first photoluminescence measurements of nanoparticles suspended in background gases. Combined with Z-contrast transmission electron microscopy (TEM) and high resolution electron energy loss spectroscopy (HREELS) analysis of individual nanoparticles, the authors investigate their fundamental light absorption and emission properties without the influence of neighboring nanoparticles or surrounding solid or liquid hosts. Such understanding is critical for the deposition of optimized films.
- Research Organization:
- Oak Ridge National Lab., Solid State Div., TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 292897
- Report Number(s):
- ORNL/CP-97379; CONF-980366-; ON: DE98004881; BR: KC0202020; TRN: AHC2DT08%%55
- Resource Relation:
- Conference: 1. NIMC international symposium on photoreaction control and photofunctional materials (PCPM`98), Tsukuba (Japan), 16-18 Mar 1998; Other Information: PBD: Feb 1998
- Country of Publication:
- United States
- Language:
- English
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