Roaming chemical reactions are a novel chapter in our understanding of certain exotic reactions relevant to molecular physics, photochemistry, and combustion chemistry. A recent finding indicated the involvement of H2 roaming for the formation of H3+ under strong-field photodissociation of certain organic molecules [Ekanayake, N. et al. Sci. Rep. 7, 4703 (2017)]. In that study, two reaction pathways for the formation of H3+ under strong-field ionization starting from a doubly-charged methanol precursor were elucidated experimentally and theoretically . This finding inspired a series of experiments aimed at elucidating aspects of its mechanisms of formation. In the present study, site-specific details and femtosecond time-resolved dynamics of H3+ formation were obtained through a combination of time-resolved mass spectrometry, photoion-photoion coincidence measurements (PIPICO) and ab initio calculations on a series of alcohols. Our findings confirm the mechanisms of this intriguing chemical process involving ultrafast double ionization of the parent molecule leading to the cleavage and formation of three chemical bonds. It was found that H3+ yield decreases as the alkane chain length increases. This new understanding will aid in the prediction of expected yields and formation times of H3+ from different organic molecules.

Strong-field laser induced H2 roaming reactions and the formation of H3+ from organic molecules

256th National Meeting (2018)

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