Strong Negative Temperature Dependence of the Simplest Criegee Intermediate CH2OO Reaction with Water Dimer.
The kinetics of the reaction of CH2OO with water vapor was measured directly with UV absorption at temperatures from 283 to 324 K. The observed CH2OO decay rate is second order with respect to the H2O concentration, indicating water dimer participates in the reaction. The rate coefficient of the CH2OO reaction with water dimer can be described by an Arrhenius expression k(T) = A exp(-Ea/RT) with an activation energy of -8.1 ± 0.6 kcal mol(-1) and k(298 K) = (7.4 ± 0.6) × 10(-12) cm(3) s(-1). Theoretical calculations yield a large negative temperature dependence consistent with the experimental results. The temperature dependence increases the effective loss rate for CH2OO by a factor of ~2.5 at 278 K and decreases by a factor of ~2 at 313 K relative to 298 K, suggesting that temperature is important for determining the impact of Criegee intermediate reactions with water in the atmosphere.
†Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.|‡Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
Mica C
MC
Smith
‡Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
Chun-Hung
CH
Chang
‡Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.|§Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Wen
W
Chao
‡Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.|§Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Liang-Chun
LC
Lin
‡Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
Kaito
K
Takahashi
†Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.|∥Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, California 94720, United States.
Kristie A
KA
Boering
‡Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.|§Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Jim Jr-Min
JJ
Lin
activation energy; atmospheric chemistry; complex formation; kinetics; transient absorption