A Study of Clusterng in Water Vapor at Ultraviolet Wavelengths.
Abstract
A device for measuring clusters in water vapor was constructed based on vacuum ultraviolet absorption techniques. Four absorption cells were built with sapphire windows to provide paths lengths of 5.0, 11.0, 76.2, and 284.5 mm. Each cell was held at a constant temperature (180 C), while the water vapor pressure was varied from 4 - 400 kPa (30 - 3000 Torr). At each pressure, an extinction coefficient was determined by measuring the differential absorption between two cells which were identical except for path length. The ultraviolet light (150 - 175 nm) was produced using a xenon, 15 kPa continuum lamp and was wavelength selected using an evacuated 1/4 meter spectrometer. The measured extinction coefficient is observed to have a water vapor density dependence stronger than linear, which may indicate the presence of clusters. Further refinements in the experimental apparatus will be necessary to provide definitive evidence for clustering of water vapor. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 10, 1981
- Accession Number
- ADA098696
Entities
People
- E. W. Smith
- J. C. Wyss
- J. Copper
- R. E. Drullinger
Organizations
- National Institute of Standards and Technology