Photodissociation dynamics of diiodomethane in solution

We have studied the photodissociation dynamics of diiodomethane (CH2I2) in acetonitrile by femtosecond pump–probe spectroscopy. The reaction was initiated using 310 nm light and the transient absorption was measured over a spectral region from 290 to 1220 nm. The wavepacket leaves the initially excited Franck–Condon region on the CH2I2 potential surface on a timescale of 350 fs. The CH2I fragment is observed within the timespan of 0.3–3 ps. The hot photoproduct, assigned to be the isomer of diiodomethane CH2I–I, appears with a characteristic time of 1 ps and vibrationally relaxes on a timescale of 10 ps.