Spectroscopic characterization of the complex between water and the simplest Criegee intermediate CH2OO Masakazu Nakajima and Yasuki Endo Citation: The Journal of Chemical Physics 140, 134302 (2014); doi: 10.1063/1.4869696 View online: http://dx.doi.org/10.1063/1.4869696 View Table of Contents: http://scitation.aip.org/content/aip/journal/jcp/140/13?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Quantum dynamical investigation of the simplest Criegee intermediate CH2OO and its O–O photodissociation channels J. Chem. Phys. 141, 134303 (2014); 10.1063/1.4894746 Detailed mechanism of the CH2I + O2 reaction: Yield and self-reaction of the simplest Criegee intermediate CH2OO J. Chem. Phys. 141, 104308 (2014); 10.1063/1.4894405 Communication: Ultraviolet photodissociation dynamics of the simplest Criegee intermediate CH2OO J. Chem. Phys. 139, 141103 (2013); 10.1063/1.4824655 Communication: Determination of the molecular structure of the simplest Criegee intermediate CH2OO J. Chem. Phys. 139, 101103 (2013); 10.1063/1.4821165 UV spectroscopic characterization of an alkyl substituted Criegee intermediate CH3CHOO J. Chem. Phys. 138, 244307 (2013); 10.1063/1.4810865

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THE JOURNAL OF CHEMICAL PHYSICS 140, 134302 (2014)

Spectroscopic characterization of the complex between water and the simplest Criegee intermediate CH2 OO Masakazu Nakajima and Yasuki Endoa) Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan

(Received 13 February 2014; accepted 17 March 2014; published online 2 April 2014) The hydrogen-bonded complex between water and the simplest Criegee intermediate CH2 OO was detected by Fourier-transform microwave spectroscopy under a jet-cooled condition. Both a-type and b-type rotational transitions were observed for H2 O–CH2 OO and D2 O–CH2 OO. The determined rotational constants enable us to conclude that the complex has an almost planar ring structure with the terminal oxygen atom of CH2 OO being a strong proton acceptor. © 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4869696] I. INTRODUCTION

Ozonolysis is an important removal process for alkenes in the troposphere.1–3 It is generally accepted that the ozonolysis of alkene is initiated by the cycloaddition of ozone to an alkene’s double bond, producing a primary organic ozonide. It decomposes to a carbonyl compound and a carbonyl oxide, R1 R2 COO, often called a Criegee intermediate (CI).4, 5 Nascent CIs from the ozonolysis of alkenes are considered to be highly excited, promptly emitting the hydroxyl (OH) radical,6, 7 the most important oxidant in the troposphere. The prompt emission of the OH radical may dominantly arise from the decomposition of hydroperoxides produced by intramolecular H-atom migration to the terminal oxygen atom. However, CIs lacking a syn-alkyl group are difficult to undergo such a proton migration, and typically isomerize to dioxirane.8 Although a 1,3-hydrogen shift to the terminal oxygen is possible for such CIs, as an example is shown in Fig. 1, large activation energy is required for surmounting a four-membered transition state (TS) of the 1,3-shift, resulting in the isomerization to dioxirane and further rearrangements. The OH emission from the nascent CIs competes with collisional relaxation, producing stabilized CIs (SCIs). Significant amounts of SCIs are considered to be consumed in the troposphere by the reaction with water.2, 9, 10 The major product of the reaction is considered to be hydroxyalkyl hydroperoxide, which may decompose to OH and a hydroxyl alkoxy radical under low pressure conditions.11–17 Recently, the reaction rate coefficients of three SCIs, CH2 OO,18 syn-, and anti-CH3 CHOO,19 with water were reported by direct kinetic studies to be