Laser based spectrophotometer for H2O traces analysis in vacuum chambers of low-temperature plasma generators
E.V. Stepanov1,2, N.N. Nikifortseva1,2, V.V. Andreev2
1Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow, Russia
2Peoples' Friendship University of Russia, Moscow, Russia
Keywords: H2O absorption spectra, analysis of trace H2O concentration, low-temperature plasma generators, tunable diode laser
Abstract
Highly sensitive analysis of neutral gas components, including H2O vapor, in high-vacuum electrical installations designed to generate low-temperature plasma is a pressing analytical and metrological challenge. This article presents a spectrophotometer based on tunable diode lasers designed for the spectral analysis of H2O traces in the vacuum chambers of low-temperature plasma generators using RF- and MW-discharges. The spectral range 7338-7370 cm-1 where vibration-rotational absorption lines of H2O of various symmetry and intensity are located was used for the analysis. Both the detection of the transmission spectra and their derivatives were used for highly sensitive analysis of traces of H2O at low pressures. The sensitivity to resonance absorption and concentration sensitivity in detecting traces of H2O in a rarefied gaseous medium were estimated.
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