Spin-Selective Processes of Electron and Nuclear Spins

A detailed knowledge of spin-selective phenomena in magnetic field is necessary for the development of molecular magnetic materialsDetailed knowledge of spin-selective phenomena in magnetic field is necessary for the development of molecular magnetic materials and for deep insight to mechanisms of many physical, chemical and biological processes. The spin conservation is an absolute requirement to any selective process. Examples of spin-selective processes are: (1) the quenching of electronically excited molecules in singlet and triplet states by paramagnetic species, (2) the generation and decay of electron spin-polarized states, intersystem crossing (ISC, Sect. 4.2.5), (3) electron, energy, and spin transfer, and magnetic isotope effect. In this chapter, the fundamentals and applications of methods based on the spin selected phenomena of dynamic nuclear polarization DNP, chemically induced spin correlated dynamic electron polarization CIDEPChemically induced spin correlated dynamic electron polarization CIDEP and chemical-induced dynamic nuclear polarization (CIDNP) have been discussed. These methods, with their capacity for monitoring radical and ion-radical intermediates, have been successfully used as effective tools for investigation of spin elective processes in chemistry, physics and biology including native and artificial photosynthesis.