THz Studies of Water Vapor
| Main Authors: | Plusquellic, David, Podobedov, Vyacheslav B., Fraser, Gerald T. |
|---|---|
| Format: | info Proceeding Journal |
| Terbitan: |
, 2006
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/17730 |
Daftar Isi:
- The types of THz absorption studies will be discussed. These include i) measurements of the water-vapor continuum from 12 ° 55 cm ° 1 (0 : 4 ° 1 : 83 THz) using a multipass cell coupled to a FIR Fourier transform spectrometer and ii) high resolution THz laser studies of the self-broadened rotational lines of water over a temperature range from 263 ° 340 K and a pressure range from 30-1400 Pa. For the continuum studies, measurements were made at a room temperature and with water vapor and nitrogen pressures up to 2.2 kPa and 81 kPa, respectively. The eÆects of the choice of lineshape function and far-wing cut-oÆ factors on the continuum absorption will be discussed. For the high resolution THz studies, the FWHM widths of pure Lorentzian lines were found to vary between 0 : 67 ° 1 : 07 cm ° 1 atm ° 1 and depend on the J , K a and K c quantum numbers as well as temperature. The observed pressure induced shifts, ±∫ (P) ; ranged from 0 : 013 ° 0 : 046 cm ° 1 atm ° 1 . The measured linewidths exhibit the (T 0 /T) n power law dependence on temperature. The best Øt exponent n varied from 0.56 to 0.81 relative to other lines in the set. A decrease in ±∫ (T) with increasing temperature was found to vary between (2-5) £ 10 ° 3 cm ° 1 atm ° 1 over the 300 ° 340 K temperature range. New developments in instrumentation will be discussed with emphasis on coupling the high-resolution THz photomixer source to the long path White cell for proposed measurements on O 2 .