From Big Medical Encyclopedia

PHOSPHORESCENCE — the luminescence proceeding some time after the termination of excitement. Unlike fluorescence (see) a phosphorescence can last from several microseconds till several o'clock. T. it is connected with transition of a molecule from the excited triplet state in the basic (see the Luminescence, the Molecule). T. it is characteristic of solid matters or the frozen solutions. It can be an important source to information on a structure of substance (see).

Bibliography: See bibliogr, to St. Luminescence.