Methyl radicals were generated in a hot-filament diamond synthesis reactor using a resistively heated tungsten filament (length, 20 mm) in a slowly flowing mixture of 0.5% CH4 in H2. The UV absorbance of CH3 was measured during deposition using a new line-of-sight optical technique called cavity ring-down spectroscopy (CRDS). Measurements were carried out at 213.9 nm, a wavelength at which the CH3 absorption cross-section has been shown by others to be independent of the temperature over a large range. We observed that the CH3 absolute concentration varied strongly as a function of the position between the substrate and the filament, and its value was strongly influenced by the substrate temperature.
CITATION STYLE
Wahl, E. H., Owano, T. G., Kruger, C. H., Zalicki, P., Ma, Y., & Zare, R. N. (1996). Measurement of absolute CH3 concentration in a hot-filament reactor using cavity ring-down spectroscopy. Diamond and Related Materials, 5(3–5), 373–377. https://doi.org/10.1016/0925-9635(95)00359-2
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