  Some basic radiative and non-radiative processes taking place in
semiconductor nanocrystals are discussed, and rates of these processes are
calculated. In particular, in the present review we explore both
intra-crystallite processes, such as the photon emission, Auger recombination,
phonon-assisted exciton relaxation, capture on surface defects, multi-exciton
generation, and inter-crystallite processes realized through the exciton
migration in ensembles of nanocrystals. Exciton transitions, creation, and
annihilation accompanied by the photon and (or) phonon emission or absorption
are considered from the point of view of their influence on the optical
properties of nanocrystals.
