Ejection dynamics of hydrogen molecular ions from methanol in intense laser fields

The ejection of hydrogen molecular ions from two-body Coulomb explosion processes of methanol (CH3OH, CD3OH and CH3OD) in an intense laser field (800 nm, 60 fs, 0.2 PW cm−2) is investigated by a coincidence momentum imaging method. From the coincidence momentum maps, the ejection processes of hydrogen molecular ions, CH3OH2+→ Hm+ + CH(3−m)OH+(m = 2, 3), CD3OH2+→ Dm+ + CH(3−m)OH+(m = 2, 3) and CH3OD2+→ Hm+ + CH(3−m)OD+(m = 2, 3), are identified. Based on the results obtained with isotopically substituted methanol, the isotope effect on the ejection process of hydrogen molecular ions is discussed. Furthermore, the ejection of H/D exchanged hydrogen molecular ions (HD+, HD2+ and H2D+) is identified, and the timescales for the H/D exchanging processes are estimated from the extent of anisotropy in the ejection directions.