Ionization of ethanol and subsequent electronic excitation in ethanol cation in intense laser fields

Itakura, Ryuji; Ikuta, Tomoya*; Hosaka, Koichi*; Akagi, Hiroshi; Yokoyama, Atsushi; Yamanouchi, Kaoru*; Kannari, Fumihiko*

Using photoelectron-photoion coincidence technique, we identify two ionization routes of ethanol to the electronic ground state and the electronically excited state of ethanol cation in intense ultraviolet (UV) laser fields (400 nm, 96 fs). The population ratio of the electronically excited state with respect to the electronic ground state of CHOH at the instant of the ionization decreases significantly as the laser intensity increases from 1.3 to 18.1 TW/cm. It is also revealed that the probability of the subsequent electronic excitation of CHOH within the same pulse is enhanced as the laser intensity increases.