Ultrafast isomerization in acetylene dication after carbon K-shell ionization.

ABSTRACT: Ultrafast proton migration and isomerization are key processes for acetylene and its ions. However, the mechanism for ultrafast isomerization of acetylene [HCCH]²⁺ to vinylidene [H₂CC]²⁺ dication remains nebulous. Theoretical studies show a large potential barrier ( > 2 eV) for isomerization on low-lying dicationic states, implying picosecond or longer isomerization timescales. However, a recent experiment at a femtosecond X-ray free-electron laser suggests sub-100 fs isomerization. Here we address this contradiction with a complete theoretical study of the dynamics of acetylene dication produced by Auger decay after X-ray photoionization of the carbon atom K shell. We find no sub-100 fs isomerization, while reproducing the salient features of the time-reso

SUBMITTER: Li Z 

PROVIDER: S-EPMC5587545 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature