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Spectroscopic Detection of Oxygen in Nitrogeneous Gas Mixtures
Author(s) -
Ross W.,
Berger D.,
Erbs H.,
Gündel H.,
Kornejew P.,
Volkmann H.
Publication year - 1991
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.2150310408
Subject(s) - metastability , oxygen , radiation , excited state , materials science , plasma , atomic physics , diffusion , analytical chemistry (journal) , irradiation , range (aeronautics) , thermal equilibrium , nitrogen , physics , chemistry , optics , thermodynamics , nuclear physics , quantum mechanics , chromatography , composite material
A pulsed high‐frequency discharge was used to excite a non‐LTE (local thermal equilibrium) plasma with a high specific power density sufficiently high to dissociate oxygen and gaseous oxides. If traces of hydrocarbons were present in the gas mixture, in the spectrum the Violet system of CN appeared with a long radiation decay time. The CN bands are excited preferentially by inelastic collisions with metastable nitrogen molecules ( A 3 σ). These levels can be efficiently depopulated by competing impact with atomic oxygen. By measuring the radiation signal during the radiation decay a dynamic range of 6 was achieved for a variation of the oxygen content between 1 and 100 ppm. The measured radiation decay of the violet CN 0–0 ‐bands at 388 nm was simulated by a simple model of rate equations valid in the time region where diffusion processes may be neglected.