History of Science and Engineering Annotation << Back DISCOVERY, INVESTIGATION AND APPLICATION OF DYNAMIC NUCLEAR POLARIZATION EFFECTS. PARTICIPATION OF SOVIET PHYSICISTS (1953–2012) A.V. Kessenikh The interaction of nuclear spins with an external magnetic fi eld and a lattice establishes through the paramagnetic relaxation process the equilibrium value of the nuclear polarization . In the presence of unpaired electron spins in the sample, it is possible to achieve a signifi cant (up to three orders) increase in the polarization by the excitation of quantum transitions at electron paramagnetic resonance (EPR) frequencies, due to electron-nuclear relaxation processes or direct pumping of populations of nuclear magnetic levels, so called dynamic nuclear polarization (DNP). The various effects of the DNP, discovered in 1953–1968, differ depending on the type of EPR spectrum. The DNP facilitates the use of experimental methods for studying the structure of chemical compounds (nuclear magnetic resonance or NMR), monitoring the transformations of biologically active substances in the body, and studying other phenomena infl uenced by the orientation of the spin and the spin magnetic moment. The dependence of the three main types of DNP effects on the EPR spectrum and a brief chronology of their discovery with participation of Soviet scientists are considered. Keywords: dynamic nuclear polarization; electron paramagnetic resonance; nuclear magnetic resonance; paramagnetic relaxation of nuclear and electron spins; Overhauser effect; solid effect; multiparticle DNP mechanisms; DNP applications in physics, chemistry, biology; Participation of Soviet physicists in the study of the DNP. DOI: 10.25791/intstg.05.2018.002 Contacts: E-mail: kessen32@mail.ru Pp. 18-31.