The term is used to identify two
radicals in close proximity in solution, within a solvent
cage. They may be formed simultaneously by some
unimolecular process, e.g. peroxide
decomposition, or they may have come together by
diffusion. While the radicals are together, correlation of the unpaired electron spins of the two species cannot be ignored: this correlation is responsible for the
CIDNP phenomenon. A radical pair is called geminate provided that each radical partner is a descendant of the same parental pair.
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1156
PAC, 1995, 67, 1307
(Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995))
on page 1363
PAC, 1996, 68, 2223
(Glossary of terms used in photochemistry (IUPAC Recommendations 1996))
on page 2270
