Infrared diode laser studies of the products from the reaction CH2($$\tilde{X}$$3B1) + O2 and from the near-UV photolysis of CH3NCS
- Univ. of California, Berkeley, CA (United States)
Absolute yields of CO, CO2, and H2CO formed in reaction of triplet methylene ($$\tilde{X}$$3B1 ≡CH2) with O2 were determined using a flash kinetic spectrometer. CH2 radicals were generated by excimer laser photolysis of ketene and product formation was monitored by time-resolved infrared diode laser absorption. Reaction was carried out in a static gas cell at room temperature at 1--25 torr. Measured product yields were CO, 0.34 ± 0.06; CO2, 0.40 ± 0.08 H2CO, 0.16 ± 0.04. Rate constants for production of CO and CO2 were equivalent to the published rate constant for removal of CH2. Indirect evidence indicated that yield of OH is 0.30 ± 0.05. Ultraviolet spectrum of methyl isothiocyanate (CH3NCS ≡ MITC) and quantum yield for dissociation into methyl isocyanide (CH3NC) and atomic sulfur at 308 nm, Φ 0.98 ± 0.24, were measured. MITC is widely used as a fumigant and readily enters the atmosphere during and after application. Results indicate that photodissociation by sunlight is an effective pathway for removal of MITC from atmosphere. A mechanism is proposed to account for the observed formation of methyl isocyanate (CH3NCO) as a secondary product in controlled laboratory studies.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 10114717
- Report Number(s):
- LBL-34918; ON: DE94005217
- Resource Relation:
- Other Information: TH: Thesis (Ph.D); PBD: Dec 1993
- Country of Publication:
- United States
- Language:
- English
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