  In this review we discuss several fundamental processes taking place in
semiconductor nanocrystals (quantum dots, QDs) when their electron subsystem
interacts with electromagnetic (EM) radiation. The physical phenomena of light
emission and EM energy transfer from a QD exciton to other electronic systems
such as neighbouring nanocrystals and polarisable 3D (semi-infinite dielectric
or metal) and 2D (graphene) materials are considered. The cases of direct
(II-VI) and indirect (silicon) band gap semiconductors are compared. We also
cover the relevant non-radiative mechanisms such as the Auger process, electron
capture on dangling bonds and interaction with phonons. The emphasis is on
explaining the underlying physics and illustrating it with calculated and
experimental results in a comprehensive, tutorial manner.
