OH formation dynamics in 193 nm photolysis of 2-methoxyethanol: A laser induced fluorescence study

•First results on dynamics of OH radical formation in the photodissociation of 2-methoxyethanol.•At least three types of mechanisms for OH radical formation is reported.•Dissociation from excited as well ground state, supported by theoretical calculation.•Effect of hydrogen bonding in the photodissociation process is reported.

Dynamics of OH radical formation in the 193 nm photolysis of 2-methoxyethanol is studied using Laser Photolysis-Laser Induced Fluorescence technique. The nascent state distribution of the OH radical is measured. The OH fragments are formed vibrationally cold, characterized by a Boltzmann-like single rotational temperature of 450 ± 100 K. The spin-orbit and Λ-doublet ratios of OH fragments are measured. The relative average translational energy of the OH channel is determined to be 17.0 ± 3.0 kcal/mol. The experimental studies along with theoretical calculations suggest a complex mechanism for OH formation consisting of at least three pathways. The prominent pathway at shorter timescale (<50 ns) involves crossing over to the nearby repulsive state, whereas, at longer timescale (>1 ms) involves a series of reaction with initial H3C-OCH2CH2OH bond cleavage, followed by rearrangement of OCH2CH2OH to CH2OCH2OH, and a final concerted step to generate OH and ethylene epoxide.

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