Continuous (in the
wavelength, not time sense)
radiation arising for example from non-quantized free-free transitions of electrons in the
fields of the ions, free-bound transitions or radiative recombinations of electrons
and ions, incandescent radiation emitted by hot solids (when the radiation distribution
conforms to that described by Planck's law, it is considered black-body radiation)
and unresolvable
band spectra, i.e. where the spectral lines are wider than the spacings between them.
Source:
PAC, 1985, 57, 1453
(Nomenclature, symbols, units and their usage in spectrochemical analysis - V: Radiation
sources (Recommendations 1985))
on page 1462