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Publication Citation: Frequency-Stabilized Cavity Ring-Down Spectrometer for High-Sensitivity Measurements of Water Vapor Concentration

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Author(s): Joseph T. Hodges; Daniel Lisak;
Title: Frequency-Stabilized Cavity Ring-Down Spectrometer for High-Sensitivity Measurements of Water Vapor Concentration
Published: January 01, 2006
Abstract: We present a portable spectrometer that uses the frequency-stabilized cavity ring-down spectroscopy technique to realize high-precision measurements of trace water vapor concentration. Measuring one of the strongest rovibrational transitions in the 1 + 3 water vapor combination band near ~ =7181:156 cm 1, we compare spectroscopic and thermodynamic determinations of tracewater vapor in N2, and nd systematic di erences attributable to water vapor background e ects and/or uncertainties in line intensities. We also compare the frequency-stabilized ring-down method with other cavity ring-down approaches that are based on unstabilized probe lasers and unstabilized ring-down cavities. We show that for the determination of water vapor concentration, thefrequency-stabilized cavity ring-down method has the minimum measurement uncertainty of these three techniques. The minimum noise-equivalent absorption coefficient of the spectrometer was 1:2 10 10 cm 1 Hz 1=2.
Citation: Applied Physics B
Volume: 85
Pages: pp. 375 - 382
Keywords: cavity ring down;hygrometer;laser spectroscopy;water vapor
Research Areas: Instrumentation, SI (Amount of Substance), Spectroscopy, Near Infra-Red, Humidity