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Infrared-laser spectroscopy using a long-pathlength absorption cell

Conference ·
OSTI ID:5751341
The absorption measurements in an ordinary cell may require typically a few torr pressure of sample gas. At these pressures the absorption lines are usually pressure-broadened and, therefore, closely spaced transitions are poorly resolved even at diode-laser resolution. This situation is greatly improved in Doppler-limited spectroscopy at extremely low sample pressures. Two very long-pathlength absorption cells were developed to be used in conjunction with diode lasers. They were designed to operate at controlled temperatures with the optical pathlength variable up to approx. 1.5 km. Not only very low sample pressures are used for studies with such cells but also the spectroscopic sensitivity is enhanced over conventional methods by a factor of 10/sup 3/ to 10/sup 4/, improving the analytical capability of measuring particle densities to the order of 1 x 10'' molecules/cm/sup 3/. This paper presents some analytical aspects of the diode laser spectroscopy using the long-pathlength absorption cells in the areas of absorption line widths, pressure broadening coefficients, isotope composition measurements and trace impurity analysis.
Research Organization:
Los Alamos National Lab., NM (USA)
DOE Contract Number:
W-7405-ENG-36
OSTI ID:
5751341
Report Number(s):
LA-UR-83-1568; CONF-831025-1; ON: DE83014197
Country of Publication:
United States
Language:
English