Communication: Long-lived neutral H_2 in hydrogen migration within methanol dication

摘要

The ejection of triatomic hydrogen molecular ions HD_2 ~+ and D_3 ~+ from CD_3OH_~(2+) is investigated by first-principle molecular dynamics simulation. Two C-D chemical bonds are found to be broken to form a neutral D_2 moiety that vibrates, rotates, and moves for a relatively long period of time (20-330 fs) towards a transition state leading to the ejection of HD_2 ~+ or D_3 ~+. The formation of such a long-lived neutral D _2 moiety within a hydrocarbon molecule interprets well the recent experimental findings of the long lifetime of doubly charged energized hydrocarbon molecules prior to the ejection of H_3 ~+.