Deuterium separation at high pressure by nanosecond CO/sub 2/ laser multiple-photon dissociation
Photochemical deuterium separation is evaluated at pressures up to 1 atm using 2 ns duration CO/sub 2/ laser pulses to achieve multiple-photon dissociation (MPD) as the isotopic separation step. Photochemical performance is compared for Freon 123 (2,2-dichloro-1,1,1-trifluoroethane), difluoromethane, and trifluoromethane based on deuterium optical selectivity in absorption, photoproduct yield, and single-step deuterium enrichment factor. The absorption coefficient versus energy fluence is measured from 0.01 to 3 J/cm/sup 2/ fluence for CF/sub 3/CDCl/sub 2/, CDF/sub 3/, and CHDF/sub 2/; added buffer gas results in an order-of-magnitude increase in the CDF/sub 3/ absorption coefficient. The deuterium optical selectivity in absorption at 0.5 J/cm/sup 2/ fluence with added buffer is 80 for CF/sub 3/CDCl/sub 2/ at 10.65 ..mu.., 800 for CHDF/sub 2/ at 10.48 ..mu.., and 2500 for CDF/sub 3/ at 10.21 ..mu... The absorption coefficients and hence optical isotopic selectivities are dependent on fluence, and the optical selectivity attains a maximum value of 8000 for CDF/sub 3/ below 0.01 J/cm/sup 2/ fluence. The deuterium-bearing MPD photoproducts at high pressure are trifluoroethylene for Freon 123, hydrogen fluoride for trifluoromethane, and both hydrogen fluoride and monofluoroacetylene for difluoromethane. Yield data determined by gas chromatography are analyzed using a model describing MPD due to a focused Gaussian beam in an absorbing medium to remove compositional and geometrical effects; this analysis results in a saturation fluence (at which the dissociation probability approaches 100%) of 12 +- 2 J/cm/sup 2/ for CF/sub 3/CDCl/sub 2/, 20 +- 2 J/cm/sup 2/ for CDF/sub 3/ buffered by 1 atm argon, 30 +- 2 J/cm/sup 2/ for CDF/sub 3/ buffered by 60--400 Torr CHF/sub 3/, and 22 +- 3 J/cm/sup 2/ for CHDF/sub 2/ buffered by 100--400 Torr CH/sub 2/F/sub 2/.
- Research Organization:
- University of California, Lawrence Livermore Laboratory, Livermore, California 94550
- OSTI ID:
- 5396524
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 72:10; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400303* -- Organic Chemistry-- Isotope Exchange & Isotope Separation-- (-1987)
CARBON DIOXIDE LASERS
CHEMICAL REACTIONS
DEUTERIUM
DISSOCIATION
FLUIDS
FLUORINATED ALIPHATIC HYDROCARBONS
FLUOROFORM
FREONS
GAS LASERS
HALOGENATED ALIPHATIC HYDROCARBONS
HIGH PRESSURE
HYDROGEN ISOTOPES
ISOTOPE SEPARATION
ISOTOPES
LASER ISOTOPE SEPARATION
LASERS
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
REFRIGERANTS
SEPARATION PROCESSES
STABLE ISOTOPES
WORKING FLUIDS