Ultrafast photofragmentation dynamics of molecular iodine driven with timed XUV and near-infrared light pulses.

Photofragmentation dynamics of molecular iodine was studied as a response to the joint illumination with femtosecond 800 nm near-infrared and 13 nm extreme ultraviolet (XUV) pulses delivered by the free-electron laser facility FLASH. The interaction of the molecular target with two light pulses of different wavelengths but comparable pulse energy elucidates a complex intertwined electronic and nuclear dynamics. To follow distinct pathways out of a multitude of reaction channels, the recoil of created ionic fragments is analyzed. The delayed XUV pulse provides a way of following molecular photodissociation of I2 with a characteristic time-constant of (55 ± 10) fs after the laser-induced formation of antibonding states. A preceding XUV pulse, on the other hand, preferably creates a 4d−1 inner-shell vacancy followed by the fast Auger cascade with a revealed characteristic time constant τA2=(23±11) fs for the second Auger decay transition. Some fraction of molecular cationic states undergoes subsequent Coulom...