Water-vapor-continuum absorption measurements (35–40 μm) using HDO-depleted water

Abstract
Longpath absorption cell measurements were performed by using 24 DF laser lines with 14.3 Torr of HDO-depleted water vapor buffered to 760-Torr pressure by an 80/20 mixture of N2/O2 at 23°C The water sample used contained one fiftieth the normal concentration of HDO. The result was a measure of the so-called water-vapor-continuum absorption in the 3.5–4.0-μm spectral region, which is approximately twice previous predictions.