Quantitative Absorption Spectroscopy of Residual Water Vapor in High-Purity Gases: Pressure Broadening of the 1.39253-mu m H2O Transition by N2, HCl, HBr, Cl2, and O2

Published

February 1, 2005

Author(s)

V Vorsa, S Dheandhanoo, S Ketkar, Joseph T. Hodges

Abstract

We determined the respective pressure-broadening coefficients of HCl, HBr and Cl2 (expressed relative to that of the reference gas N2) for the (n1n2n3)JKa,Kc = (0,0,0)30,3 (1,0,1)20,2 rovibrational transition of H216O, occurring at 1.39253 m. The experiment used a continuous wave cavity ring-down spectroscopy analyzer to measure the peak absorption losses as a function of added moisture concentration. The measured pressure-broadening coefficients for HCl, HBr and Cl2 are 2.76, 2.60 and 1.48 times respectively, that of the N2 pressure-broadening coefficient, and detection limits for water vapor range from 0.4 nmol mol-1 for the N2-bulk-gas case to 2.3 nmol mol-1 for the HBr-bulk-gas case. The degradation of detection limit (relative to the N2-bulk-gas) case is ascribed to pressure-broadening-induced reduction in peak absorption cross-section and to elevated background loss from the bulk gas.

Citation

Applied Optics

Volume

44

Issue

No. 4

Pub Type

Journals

Keywords

absorption spectroscopy, cavity ring-down, corrosive gas, pressure broadening, water vapor

Citation

Vorsa, V. , Dheandhanoo, S. , Ketkar, S. and Hodges, J. (2005), Quantitative Absorption Spectroscopy of Residual Water Vapor in High-Purity Gases: Pressure Broadening of the 1.39253-mu m H₂O Transition by N₂, HCl, HBr, Cl₂, and O₂, Applied Optics (Accessed October 9, 2025)