Determination of Photoinduced Radical Generation Quantum Efficiencies by Combining Chemical Actinometry and ¹⁹F NMR Spectroscopy

We introduce a general and relatively straightforward protocol aimed at determining the absolute photoinduced radical generation efficiency via NMR monitoring. This approach relies on use of scavenger probe that combines nitroxide moiety specifically reacts with radicals trifluoromethyl group used as 19F signaling unit. Using an LED source, whose fluence is precisely determined by chemical actinometry procedure also described herein, method to determine photogeneration quantum yields three well-known polymerization initiators: azobisisobutyronitrile (AIBN), 4,4'-bis(N,N-diethylamino)benzophenone (BDEBP, derivative Michler's ethyl ketone), 2,4,6-trimethylbenzoyl diphenylphosphine oxide (MAPO). The overall good agreement values previously reported in literature proves robustness this new method. then extended study precise measurement yield free-radical newly synthesized photoinitiator for two-photon direct laser writing. highlights potential methodology quantitative determination many fields applications.