Separation of O, C, and S isotopes by two-step, laser photodissociation of OCS

Journal Article · Thu Dec 15 04:00:00 EST 1983 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.445782· OSTI ID:5557885

Zittel, P F; Darnton, L A; Little, D D

Isotopes of O, C, and S have been separated by two-step, laser photodissociation of OCS. The technique utilizes isotopically selective vibrational excitation of OCS in the ..nu../sub 2/ (bending) vibrational mode with a line-tuned CO/sub 2/ laser (lambdaapprox.9.4 ..mu..m), followed by photodissociation with a KrF excimer laser (lambda = 249 nm) and chemical scavenging of the sulfur atoms. Enrichment factors ranging from 1.5 to 3.5 were obtained for different isotopes. A sensitive IR absorption apparatus was used to measure absorption of the high energy CO/sub 2/ laser pulse by OCS as a function of pressure and laser fluence. Average absorptions ranging up to 1.5 photons/molecule were attributed to rapid rotational relaxation and in part to sequential absorption up the ladder of ..nu../sub 2/ vibrational levels. The 249 nm photodissociation cross section of OCS was measured as a function of absorbed IR energy. An excitation of one CO/sub 2/ laser photon per molecule, or two quanta of ..nu../sub 2/ vibration per molecule, increased the photodissociation cross section by a factor of 9 over the thermal (295 K) cross section. A rate constant of (4.8 +- 1.0) x 10/sup 5/ s/sup -1/ Torr/sup -1/ was inferred for the exchange of ..nu../sub 2/ vibrational energy between isotopic varieties of OCS.

• Research Organization: Chemistry and Physics Laboratory, The Aerospace Corporation, Los Angeles, California 90009
• OSTI ID: 5557885
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 79:12; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400203* -- Isotope Exchange & Isotope Separation-- (-1987)
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON OXYSULFIDE
CHEMICAL REACTIONS
DECOMPOSITION
DISSOCIATION
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
ISOTOPE SEPARATION
ISOTOPES
LASER ISOTOPE SEPARATION
OXYGEN ISOTOPES
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
SEPARATION PROCESSES
SULFUR COMPOUNDS
SULFUR ISOTOPES
VIBRATIONAL STATES