The field of spin chemistry includes the magnetic field effects (MFEs) and magnetic isotope effects (MIEs) on chemical and biochemical reactions through radical pairs as well as chemically induced dynamic nuclear polarization (CIDNP) and chemically induced dynamic electron polarization (CIDEP). These phenomena have successfully been explained in terms of the radical pair mechanism (RPM). This paper introduces the fundamentals of spin chemistry, special attention being paid to applications of strong magnetic fields applied with superconducting and pulsed magnets. First, the basic principles of the RPM are described. Here, the conversion rate between the singlet and triplet radical pairs is shown to be appreciably influenced by not only ordinary magnetic fields less than 2 T, but also nuclear spins in the radical pairs. Second, typical results of MFEs on photochemical reactions in solutions that have been obtained by the author's group are reviewed. Using superconducting magnets (B ≤ 10 T) and pulsed magnets (B ≤ 30 T), the author applied strong magnetic fields to find new MFEs in photochemical reactions. Finally, this paper reviews the prospects of spin chemistry, where the effects of environmental electromagnetic fields on human diseases are also discussed.
