WATER-VAPOR CONTINUUM IN THE 15-MU TO 25-MU-M SPECTRAL REGION - EVIDENCE FOR (H2O)2 IN THE ATMOSPHERE

Recent investigations of the atmospheric transmittance in the 15- to 2 5-mum spectral region have produced experimental results of the absorp tion of the water vapor continuum. From these results it is evident th at the excessive absorption of the water vapor (the water continuum) c annot be explained simply by the theoretical continuum model based on the modified impact theory and the Van Vleck-Huber model of line broad ening. The measured continuum absorption has spectral features similar to those roughly predicted by the water dimer theory. A quantitative agreement between the experimental results and the prediction accordin g to the dimer theory was found.