Photochemistry and kinetics of gas phase reactions involving HO and Cl radicals

Technical Report · Sat Nov 01 04:00:00 EST 1980

DOI:https://doi.org/10.2172/6822615· OSTI ID:6822615

Nelson, H H

The kinetics of the reaction of the HO radical with HNO/sub 3/ and H/sub 2/O/sub 2/, the kinetics of Cl atom reactions with ClNO and ClNO/sub 2/, and the photochemistry of ClNO/sub 2/ and ClONO/sub 2/ were examined. The ultraviolet absorption cross sections of HNO/sub 3/ and ClNO/sub 2/ were also determined as part of the kinetics work. The rate constant for the reaction of HO with HNO/sub 3/ at room temperature was measured to be (8.2 +- 1.8) x 10/sup -14/ cm/sup 3/ molecule/sup -1/ s/sup -1/, where the uncertainty reported here and in all cases reflects twice the experimental standard deviation plus an estimate of systematic errors. The rate constant for the reaction HO + H/sub 2/O/sub 2/ was measured as (1.57 +- 0.23) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/. This agrees well with the two latest determinations and serves as a calibration of the experimental apparatus used. The Cl + ClNO reaction rate constant was determined to be (1.65 +- 0.32) x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/. The rate constant for the reaction of Cl + ClNO/sub 2/ was found to be (5.05 +- 0.75) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/. This is the first direct measurement of this rate constant. The photodissociation of ClNO/sub 2/ was studied in great detail. The absorption cross sections were measured in the ultraviolet and found to be substantially lower than the literature values in the Cl/sub 2/ absorption region (300 to 360 nm). Two product channels were investigated; products representative of the two channels were Cl and O atoms. Absolute calibration for the product detection systems was provided by Cl/sub 2/ and NO/sub 2/ photolysis respectively. The quantum uields measured for photolysis at 350 nm, calcualted using the absorption spectrum measured in this work, are: 0.93 +- 0.1 for Cl and less than or equal to 0.025 for O. An upper limit of 0.1 was measured for the O atom channel in ClOHO/sub 2/ photolysis.

• Research Organization: California Univ., Berkeley (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6822615
• Report Number(s): LBL-11666
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
CHEMICAL REACTION KINETICS
CHEMISTRY
CHLORINE
CHLORINE COMPOUNDS
CROSS SECTIONS
ELEMENTS
HALOGEN COMPOUNDS
HALOGENS
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
HYDROXYL RADICALS
INORGANIC ACIDS
KINETICS
NITRIC ACID
NITROGEN COMPOUNDS
NONMETALS
OXYGEN COMPOUNDS
PEROXIDES
PHOTOCHEMISTRY
RADICALS
REACTION KINETICS