First CRDS-measurements of water vapour continuum in the 940 nm absorption band

Abstract Measurements of near-infrared water vapour continuum using continuous wave cavity ring down spectroscopy (cw-CRDS) have been performed at around 10611.6 and 10685.2 cm - 1 . The continuum absorption coefficients for N 2 -broadening have been determined to be C F 296 K = ( 1.0 ± 0.2 ) × 10 - 24 cm 2 mol - 1 atm - 1 and C F 278 K = ( 1.8 ± 0.4 ) × 10 - 24 cm 2 mol - 1 atm - 1 at 10611.6 cm - 1 , and C F 296 K = ( 1.6 ± 0.5 ) × 10 - 24 cm 2 mol - 1 atm - 1 and C F 278 K = ( 2.1 ± 0.4 ) × 10 - 24 cm 2 mol - 1 atm - 1 at 10685.2 cm - 1 , respectively. These results represent the first near-IR continuum laboratory data determined within the complex spectral environment in the 940 nm water vapour band and are in reasonable agreement with simulations using the semiempirical CKD formulation.