Time-resolved (e, 2e) electron momentum spectroscopy on the toluene S₁ excited state

We report a time-resolved (e, 2e) experiment on the toluene molecule in the S₁(π, π∗) state. The toluene S₁ state was prepared by a 267 nm pump laser and probed with electron momentum spectroscopy using a 1.2 keV incident electron beam consisting of a train of 4 or 8 ultrashort electron pulses (∼ 1 ps) with 0.3 or 0.7 ns intervals. In spite of the low data statistics, the experimental results clearly demonstrate that the present technique selectively probes ionization transition to two-hole-one-particle configurations that are hardly accessible from the ground electronic state.