Dissociation dynamics of propargyl chloride molecular ion near the reaction threshold: Manifestation of quantum mechanical tunneling

Dong Shin Won, Joong Chul Choe, Myung Soo Kim

Research output: Contribution to journalArticlepeer-review

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Abstract

The Cl loss from the propargyl chloride molecular ion has been investigated using mass-analyzed ion kinetic energy spectrometry (MIKES). The kinetic energy release distribution in the unimolecular dissociation has been determined. The potential energy surface for the mechanistic pathway has been calculated at the B3LYP/6-311G density functional theory level. The calculated potential energy surface suggested that the threshold dissociation of the propargyl chloride molecular ion produces the C3H+3 ion, only with the cyclopropenium structure, and with the release of a large amount of kinetic energy. This is in agreement with experimental results. Also, calculation of the rate constants with statistical rate models predicted that the reaction observed on a microsecond time scale occurs via tunneling through the rate-determining isomerization barrier for H-atom transfer. It has been found that a broad lifetime distribution is a manifestation of quantum mechanical tunneling of a precursor prepared under thermal conditions. Reinterpretation of previous photoelectron-photoion coincidence results taking into account the tunneling effect necessitated raising the critical energy to 0.64 eV from the energy of 0.34 eV reported previously. Copyright (C) 2000 John Wiley and Sons, Ltd.

Original languageEnglish
Pages (from-to)1110-1115
Number of pages6
JournalRapid Communications in Mass Spectrometry
Volume14
Issue number13
DOIs
StatePublished - 2000

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