Basic principles and applications of spin chemistry (a brief review) Maria Vyushkova Notre Dame Radiation Laboratory, April 2011 Outline What is spin chemistry? Definition, history & introductory notes Radical pairs, radical pair reaction mechanism, spin correlation in a pair Methods of radical pair generation/detection of products CIDEP and CIDNP 2/29 Methods of radical pair generation To create radicals, it usually requires the input of external energy: UV/visible light (photochemical generation) photo-CIDNP – the most ubiquitous spin chemistry technique SNP, RYDMR, MARY, time resolved EPR Ionizing irradiation (radiation chemistry) radiofluorescence techniques: OD EPR, MARY, quantum beats spectroscopy; time resolved EPR 19/29 Photochemical generation: Absorbing molecules of photosensitizer in a “transparent” solvent => selective and uniform production of the excited solute molecules Decomposition/electron transfer of the excited state (S1 or T1) of the precursor Both singlet and triplet-born radical pairs (ISC mechanism) Generation of radical pairs by ionizing radiation: an “overkill” method in terms of photon/particle energy each photon/particle produces many ionizations/excited states along its track the “bulk” solvent molecules are ionized/excited 22/29 References (what to read on spin chemistry) 1. K.M. Salikhov, Yu.N. Molin, R.Z. Sagdeev, A.L. Buchachenko. Spin Polarization and Magnetic Effects in Radical Reactions. Elsevier, Amsterdam-Oxford-New York-Tokyo, 1984 2. U.E. Steiner and T. Ulrich. Magnetic Field Effects in Chemical Kinetics and Related Phenomena // Chem. Rev. 1989, 89, p, 51-147 3. H. Hayashi. Introduction to Dynamic Spin Chemistry. Magnetic Field Effects on Chemical and Biochemical Reactions. World Scientific, 2004 4. J.R. Woodward. Radical Pairs in Solution. //Progress in Reaction Kinetics and Mechanism, 2002, 27, p. 65-207 29/29.