Accession Number : AD0482685

Title :   ABSORPTION OF LIGHT IN GASES.

Descriptive Note : Annual technical summary rept. no. 1, 1 Nov 64-31 Jan 66,

Corporate Author : PERKIN-ELMER CORP NORWALK CT ELECTRO-OPTICAL DIV

Personal Author(s) : Atwood, John G. ; Golay, Marcel J. E. ; Tobin, Marvin C. ; Appleman, Sidney ; Kerr, Edwin L.

Report Date : 15 APR 1966

Pagination or Media Count : 38

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.

Descriptors :   *ABSORPTION SPECTRA), (*GASES, ABSORPTION, LIGHT, LIGHT PULSES, LASERS, RUBY, EXCITATION, ELECTROSTRICTION, RELAXATION TIME, SENSITIVITY, BANDWIDTH, ACOUSTIC IMPEDANCE, MEMBRANES, REFLECTIVITY, ATTENUATION, ATMOSPHERES, MEASUREMENT, MICROPHONES, HIGH FREQUENCY, WATER VAPOR.

Subject Categories : Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE