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The prompt transfer of cutting-edge science into students’ curricula is a challenging task. Often research experiments are too complex or expensive to be translated into a secondary or tertiary education setting. Herein, we introduce a laboratory experiment that translates the recently developed research technique of a wavelength dependent, photochemical action plot into a student accessible format. The practical incorporates aspects of photophysics, required to calculate a constant photon emission from each different colored LED, as well as polymer chemistry in understanding the mechanism and quantitatively determining the polymerization conversion. During this practical the students (i) learn about areas where photochemical reactions are used to generate everyday materials, (ii) understand and apply the concepts of absorption and Beer–Lambert’s law, (iii) record and evaluate a photochemical action plot, and (iv) critically discuss the disparate nature of action and absorption spectra to generate an understanding of the implications for photochemical material design.

The reactions of methyl radicals with large (up to C(96)H(24)) polycyclic aromatic hydrocarbons (PAHs) are studied by density functional calculations to shed light on the experimentally observed deposition of carbon on highly oriented pyrolytic graphite (HOPG), which occurs when hot HOPG (decorated by nanometre-sized defects) is exposed to methyl radicals. The equilibrium structures of the reaction products, together with transition structures for PAHs up to the size of phenanthroperylene, are determined using the density functionals B3LYP, TPSSh, BP86 and TPSS. The structures are analysed by computing the pi orbital axis vector (POAV) and the altitude of the reactive carbon above the molecular plane of the PAH. The strongest C-CH(3) bonds are found at the edges of the PAHs, where the s character of the C orbital involved in the bond is roughly 25 % (sp(3) hybrid orbital). Carbon atoms inside the PAH form bonds with the methyl radical through atomic orbitals with about 16 % s character in the POAV analysis. These bonds are much weaker than those at the edges of the PAH, while the reactive carbon has moved about 40 pm above the molecular plane. At the edges, the PAH carbon atoms do not leave the molecular plane to this extent. The computed barrier heights and geometrical parameters of the transition structures are in agreement with Hammond's postulate, and the relative energies of all of the equilibrium structures can be rationalized by Hückel molecular orbital (HMO) theory.