Electronic Resource
Woodbury, NY
:
American Institute of Physics (AIP)
Applied Physics Letters
67 (1995), S. 144-146
ISSN:
1077-3118
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The spatial profile of methyl radical concentration in a hot-filament reactor has been measured using cavity ring-down spectroscopy (CRDS) at a wavelength of 213.9 nm for which the CH3 absorption cross section has been shown to be nearly independent of temperature. Methyl radicals are generated with a 25 mm long tungsten filament heated to 2400 K in a slowly flowing mixture of 0.6% CH4 in H2 (20 Torr total pressure). CRDS is employed to measure CH3 absorbance as a function of a distance perpendicular to the axis of the filament. The CH3 absorbance profiles do not change when the direction of the process gas flow through the reactor is reversed, which indicates cylindrical symmetry of the CH3 distribution about the filament. Consequently, the radial CH3concentration in the reactor is determined by Abel inversion of the CH3 absorbance profile. The CH3concentration peaks ∼4 mm from the filament (1.04×1014molecules/cm3). Methyl radicals decay rapidly as a function of a distance from the filament and disappear about 2 cm from the filament within our present detection sensitivity (3×1012molecules/cm3). © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.115475
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