Our paper reports a combined experimental and computational investigation of the electrostatic tuning of Irgacure 2959, a Norrish-type I photoinitiator, in the presence of bound cations (H+ , Li+ , Na+ , K+ , Zn2+ , Ca2+ and Mg2+). Laser photodissociation action spectroscopy is deployed to acquire photodissociation spectra of mass- selected cation complexes. Quantum chemical calculations (TD-DFT and SCS-CC2) reveal that the cations are acting as point charges such that shifts of the key ππ* and nπ* states can be modelled as perturbations by an oriented electric field (OEF). The model agrees with the experimental photodissociation action spectra.
Irgacure paper SI Xiv