ABSORPTION OF LIGHT IN GASES.
Abstract
Two methods of measuring optical molecular absorptivities in gases, potentially capable of approaching theoretical sensitivity limits of 10 to the -10th power/cm are under study. An acoustic method was pushed experimentally to a sensitivity of 10 to the -5th power/cm absorptivity. Practical obstacles to further improvement have been found for the acoustic method. The second method, a laser illuminated spectrophone, is now being investigated. It promises to reach closer to the theoretical limit. Both methods use a Q-switched ruby laser, tunable from pulse to pulse over a 2A range, as the excitation source. Absorbed light causes a temperature rise and expansion of the gas sample. In the acoustic method the expansion starts cylindrically propagating sound disturbances. These are focused by acoustic mirrors onto a membrane detector. In the spectrophone method the gas sample is enclosed in a sealed glass tube. The gas expansion causes a pressure rise which is transmitted to the membrane detector through a short duct.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 15, 1966
- Accession Number
- AD0482685
Entities
People
- Edwin L. Kerr
- John G. Atwood
- Marcel J. E. Golay
- Marvin C. Tobin
- Sidney Appleman