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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 20, Number 12
BKCSDE 20(12)
December 20, 1999 

Temporal Evolution and Ablation Mechanism of Laser-induced Graphite Plume at 355 nm
Young-Ku Choi, Hoong-Sun Im, Kwang-Woo Jung
Expansion dynamics of C + ions ejected from 355-nm laser ablation of graphite target in vacuum has been investigated by pulsed-field time-of-flight (TOF) mass spectrometry. A strong nonlinear dependence of the amount of desorbed C + ions on laser fluence is interpreted by the mechanism that C + ions are produced directly from the graphite via conversion of the multiphoton energy into thermal energy. The temporal evolution of C + ions was measured by varying the delay time of the ion repelling pulse with respect to the laser irradiation, which provides significant information on the ablated plume characterization. The TOF distributions of ablated ions showed a bimodal shape and could be fitted by shifted Maxwell-Boltzmann distributions. The velocity of the fast component increases with the delay time, whereas the slow component (< 500 m/s) exhibits a constant velocity. Also studied were the effects of the laser fluence on the energetics of C + ions.
1501 - 1505
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