ISSN:
1432-0649
Keywords:
PACS:33.50D; 42.65C; 81.15H
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract. Resonance enhanced CARS and LIF have been applied to the CH radicals in a microwave excited Ar/H $_2$ /CH $_4$ plasma ( $p = 21$ Pa, $P_{\rm Mikro} = 2.7$ kW). Both techniques yield similar nonthermal rotational population distributions of CH(X $^2\Pi_r$ ) in its vibrational ground state ( $v=0$ ), which can be described by two rotational temperatures, $T_{\rm rot,1} \approx 600$ K being in the order of the gas temperature for rotational states with $N \le 7$ , and a considerably higher $T_{\rm rot,2}$ for the higher rotational states. This result is in good agreement with previous resonance CARS and LIF measurements in similar plasmas. With resonance CARS additional measurements on CH in the $v=1$ state could be performed yielding a vibrational temperature of 2440 K, the total CH density was about $1.6 \times 10^{18}$ m $^{-3}$ . The detection limits of both techniques are determined, in our case about $2 \times 10^8$ CH radicals per quantum state in the detection volume, and their advantages and disadvantages are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s003400050153
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