Attosecond spectroscopy reveals alignment dependent core-hole dynamics in the ICl molecule

The removal of electrons located in the core shells of molecules creates transient states that live between a few femtoseconds to attoseconds. Owing to these short lifetimes, time-resolved studies of these states are challenging and complex molecular dynamics driven solely by electronic correlation are difficult to observe. Here, we obtain few-femtosecond core-excited state lifetimes of iodine monochloride by using attosecond transient absorption on iodine 4d(-1)6p transitions around 55eV. Core-level ligand field splitting allows direct access of excited states aligned along and perpendicular to the ICl molecular axis. Lifetimes of 3.50.4fs and 4.3 +/- 0.4fs are obtained for core-hole states parallel to the bond and 6.5 +/- 0.6fs and 6.9 +/- 0.6fs for perpendicular states, while nuclear motion is essentially frozen on this timescale. Theory shows that the dramatic decrease of lifetime for core-vacancies parallel to the covalent bond is a manifestation of non-local interactions with the neighboring Cl atom of ICl. Here the authors report a study measuring lifetimes of core-hole states of ICl molecule using attosecond transient absorption spectroscopy. They find that lifetimes depend on the alignment of the orbital relative to the molecular axis.