C8.
CW cavity ring down spectroscopy through a supersonic planar plasma
P. Birza1, T. Motylewski1, D. Khoroshev1, A. Chirokolava1,
H. Linnartz1,2 and J.P. Maier1
1Department of Chemistry, Klingelbergstrasse 80, CH 4056 Basel
2Fysische Chemie, Vrije Universiteit Amsterdam, De Boelelaan 1083,
NL 1081 HV Amsterdam
A recently constructed high resolution setup for the detection of carbon chain radicals in the gas phase is presented. The setup consists of a tunable cw laser that is used to sample a supersonic planar plasma generated by discharging a high pressure gas pulse of acetylene in He in a multilayer slit nozzle geometry. Continuous wave cavity ring down spectroscopy is used as a sensitive detection scheme.
The method combines sensitivity with high spectral resolution. The poster describes in all details the difficulties that must be overcome when implementing a pulsed discharge in the cavity. The performance is demonstrated on the example of a completely rotationally resolved spectrum of the origin band of the A2u – X2g electronic transition of the triacetylene cation, HC6H+.
Part of the trigger scheme necessary to “chase” a resonance in a cw CRD experiment. A piezo voltage is used to scan the cavity length, inducing cavity resonances. The trigger scheme is made in such a way that plasma pulse and CRD event will overlap, even though the plasma causes a number of additional instabilities.
More information is available from Chem. Phys. 283 (2002) 119.
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