Temperature-dependent branching ratios of deuterated methoxy radicals (CH 2DO•) reacting with O 2

Hongyi Hu; Theodore S. Dibble; Geoffrey S. Tyndall; John J. Orlando

doi:10.1021/jp211873w

Temperature-dependent branching ratios of deuterated methoxy radicals (CH ₂DO•) reacting with O ₂

Hongyi Hu, Theodore S. Dibble, Geoffrey S. Tyndall, John J. Orlando

Experimental Science Section

Research output: Contribution to journal › Article › peer-review

8 Scopus citations

Abstract

The methoxy radical is an intermediate in the atmospheric oxidation of methane, and the branching ratio (k _1a/k _1b) (CH ₂DO• + O ₂ → CHDO + HO ₂ (1a) and CH ₂DO• + O ₂ → CH ₂O + DO ₂ (1b)) strongly influences the HD/H ₂ ratio in the atmosphere, which is widely used to investigate the global cycling of molecular hydrogen. By using the FT-IR smog chamber technique, we measured the yields of CH ₂O and CHDO from the reaction at 250-333 K. Kinetic modeling was used to confirm the suppression of secondary chemistry. The resulting branching ratios are well fit by an Arrhenius expression: ln(k _1a/k _1b) = (416 ± 152)/T + (0.52 ± 0.53), which agrees with the room-temperature results reported in the only previous study. The present results will be used to test our theoretical understanding of the role of tunneling in the methoxy + O ₂ reaction, which is the prototype for the entire class of alkoxy + O ₂ reactions.

Original language	English
Pages (from-to)	6295-6302
Number of pages	8
Journal	Journal of Physical Chemistry A
Volume	116
Issue number	24
DOIs	https://doi.org/10.1021/jp211873w
State	Published - Jun 21 2012

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@article{2c74a7453118482d806893f9dc0ca0b6,

title = "Temperature-dependent branching ratios of deuterated methoxy radicals (CH 2DO•) reacting with O 2 ",

abstract = "The methoxy radical is an intermediate in the atmospheric oxidation of methane, and the branching ratio (k 1a/k 1b) (CH 2DO• + O 2 → CHDO + HO 2 (1a) and CH 2DO• + O 2 → CH 2O + DO 2 (1b)) strongly influences the HD/H 2 ratio in the atmosphere, which is widely used to investigate the global cycling of molecular hydrogen. By using the FT-IR smog chamber technique, we measured the yields of CH 2O and CHDO from the reaction at 250-333 K. Kinetic modeling was used to confirm the suppression of secondary chemistry. The resulting branching ratios are well fit by an Arrhenius expression: ln(k 1a/k 1b) = (416 ± 152)/T + (0.52 ± 0.53), which agrees with the room-temperature results reported in the only previous study. The present results will be used to test our theoretical understanding of the role of tunneling in the methoxy + O 2 reaction, which is the prototype for the entire class of alkoxy + O 2 reactions.",

author = "Hongyi Hu and Dibble, \{Theodore S.\} and Tyndall, \{Geoffrey S.\} and Orlando, \{John J.\}",

year = "2012",

month = jun,

day = "21",

doi = "10.1021/jp211873w",

language = "English",

volume = "116",

pages = "6295--6302",

journal = "Journal of Physical Chemistry A",

issn = "1089-5639",

publisher = "American Chemical Society",

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TY - JOUR

T1 - Temperature-dependent branching ratios of deuterated methoxy radicals (CH 2DO•) reacting with O 2

AU - Hu, Hongyi

AU - Dibble, Theodore S.

AU - Tyndall, Geoffrey S.

AU - Orlando, John J.

PY - 2012/6/21

Y1 - 2012/6/21

N2 - The methoxy radical is an intermediate in the atmospheric oxidation of methane, and the branching ratio (k 1a/k 1b) (CH 2DO• + O 2 → CHDO + HO 2 (1a) and CH 2DO• + O 2 → CH 2O + DO 2 (1b)) strongly influences the HD/H 2 ratio in the atmosphere, which is widely used to investigate the global cycling of molecular hydrogen. By using the FT-IR smog chamber technique, we measured the yields of CH 2O and CHDO from the reaction at 250-333 K. Kinetic modeling was used to confirm the suppression of secondary chemistry. The resulting branching ratios are well fit by an Arrhenius expression: ln(k 1a/k 1b) = (416 ± 152)/T + (0.52 ± 0.53), which agrees with the room-temperature results reported in the only previous study. The present results will be used to test our theoretical understanding of the role of tunneling in the methoxy + O 2 reaction, which is the prototype for the entire class of alkoxy + O 2 reactions.

AB - The methoxy radical is an intermediate in the atmospheric oxidation of methane, and the branching ratio (k 1a/k 1b) (CH 2DO• + O 2 → CHDO + HO 2 (1a) and CH 2DO• + O 2 → CH 2O + DO 2 (1b)) strongly influences the HD/H 2 ratio in the atmosphere, which is widely used to investigate the global cycling of molecular hydrogen. By using the FT-IR smog chamber technique, we measured the yields of CH 2O and CHDO from the reaction at 250-333 K. Kinetic modeling was used to confirm the suppression of secondary chemistry. The resulting branching ratios are well fit by an Arrhenius expression: ln(k 1a/k 1b) = (416 ± 152)/T + (0.52 ± 0.53), which agrees with the room-temperature results reported in the only previous study. The present results will be used to test our theoretical understanding of the role of tunneling in the methoxy + O 2 reaction, which is the prototype for the entire class of alkoxy + O 2 reactions.

UR - https://www.scopus.com/pages/publications/84862694190

U2 - 10.1021/jp211873w

DO - 10.1021/jp211873w

M3 - Article

C2 - 22432871

AN - SCOPUS:84862694190

SN - 1089-5639

VL - 116

SP - 6295

EP - 6302

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

IS - 24

ER -

Temperature-dependent branching ratios of deuterated methoxy radicals (CH ₂DO•) reacting with O ₂

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