Gated ICCD photography of the KrF-laser ablation of graphite into background gases
The interaction of a laser-generated ablation plume with a background gas is of current interest for several materials-fabrication applications. During pulsed laser deposition (PLD) of thin films by laser ablation, for example, an ambient back ground gas (pressure usually {<=} 300 mTorr) is often employed. The dynamics of the KrF-laser ablation ({Phi} = 20 J cm{sup {minus}}) of graphite into 300 Torr of He, Ne, Ar, and Xe has been studied by fast imaging of the visible plasma emission using a gated intensified CCD array (ICCD) camera system. In each case, the soot which was redeposited on the graphite rod following ablation was highly fullerene deficient compared to the material collected on a sample disk 1.5 cm from the rod, as determined by laser desorption Fourier Transform Mass Spectrometry (FTMS). The ICCD photographic investigations of the plasma plume propagation in the different gases reveal three common phases to the expansions: (1) forward motion, deceleration and stopping of the leading edge of the plume, (2) an apparent reflected shock within the plume which propagates backward and partially reflects from the rod surface, leaving ``redeposited`` material, (3) a secondary forward propagation and coalescence of the material reflected from the rod surface, resulting in continued expansion and dissipation of the plasma and the appearance of glowing ultrafine particles. Detailed sequencing of the plasma expansion into argon is presented here which shows at least two sets of reflected shocks. The possible explanation of the observed difference in fullerene content is discussed on the basis of different plasma phases resulting in soot deposition on the rod and disk.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 10178445
- Report Number(s):
- CONF-9308122-20; ON: DE94017882; TRN: AHC29421%%129
- Resource Relation:
- Conference: International Union of Materials Research Societies on advanced materials,Tokyo (Japan),31 Aug - 4 Sep 1993; Other Information: PBD: Jul 1993
- Country of Publication:
- United States
- Language:
- English
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