Communication: long-lived neutral H2 in hydrogen migration within methanol dication

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Molecular Dynamics

Background:

• Doubly charged hydrocarbon molecules exhibit surprisingly long lifetimes before fragmenting.
• The mechanisms governing the stability and dissociation pathways of these energetic species are not fully understood.

Purpose of the Study:

• To investigate the ejection mechanisms of HD2(+) and D3(+) ions from doubly charged methanol (CD3OH2+).
• To elucidate the role of intermediate species in the dissociation dynamics of energetic molecular ions.

Main Methods:

• First-principle molecular dynamics simulations were employed.
• The simulations tracked the breaking of chemical bonds and the behavior of resulting molecular fragments.

Main Results:

• The breaking of two C-D bonds was observed, leading to the formation of a neutral D2 moiety.
• This D2 moiety exhibited prolonged vibration, rotation, and movement (20-330 fs) before reaching a transition state.
• The dynamics facilitate the subsequent ejection of HD2(+) or D3(+) ions.

Conclusions:

• The formation of a long-lived neutral D2 intermediate explains the extended lifetimes of doubly charged hydrocarbon molecules.
• This finding provides a theoretical basis for recent experimental observations of stable energetic molecular ions.