Low-uncertainty H 2O line intensities for the 930-nm region

Abstract

We measured room-temperature H 2O spectra of the 3 ν polyad within the wave number range 10 603 cm −1 to 10 852 cm −1 using frequency-stabilized cavity ring-down spectroscopy. More than 70 transitions, divisible into two groups based on their relative intensities (strong and weak) were investigated. For the 23 lines comprising the set of strong transitions, the water vapor sample was prepared as a dilute mixture in a steady flow of N 2 carrier gas, and the measurement of the water vapor sample number density was linked to primary methods of humidity generation. For these strong transitions, the measured line intensities were within 1% of previous measurements. The line intensity measurements of the weaker H 2O transitions, were made on samples of static pure water vapor, and these results were systematically greater than previous measurements by approximately 20%.