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High- Resolution Cavity Ring-Down Spectroscopy Measurements of Blended H20 Transitions



D Lisak, Joseph T. Hodges


We probed four closely spaced rovibrational water vapor absorption transitions near wavenumber = 7100 cm(^-1) using frequency-stabilized cavity ring-down spectroscopy. Room-temperature spectra were acquired for pure water vapor in the Doppler limit and for mixtures containing 6.6 umol mol^-1 of water vapor in N2 at total gas pressures ranging from 6.5 kPa to 53 kPa. By measuring Lamb dips for each transition, we demonstrated a resolution of 50 kHz and determined relative transition frequencies with an uncertainty <0.4 MHz over a 10 GHz range. Pressure-induced broadening, collisional narrowing coefficients of the component transitions and line areas were retrieved by fits of model line shapes to the measured spectra. Standard and advanced models were considered including those which incorporated the combined effects of collisional narrowing and speed-dependent line broadening and line shifting. By measuring water vapor concentration with a transfer standard hygrometer, we determined line intensities in terms of measured line areas with a combined relative uncertainty of 0.6%.
Applied Physics B


cavity ringdown spectroscopy, high-resolution, lamb-dips, line-intensity, pressure-broadening, water vapor


Lisak, D. and Hodges, J. (2007), High- Resolution Cavity Ring-Down Spectroscopy Measurements of Blended H<sub>2</sub>0 Transitions, Applied Physics B (Accessed April 18, 2024)
Created December 31, 2006, Updated October 12, 2021