A plot of the spectral radiant exitance or of the spectral photon exitance against the frequency (or wavenumber, or wavelength) of excitation. When corrected for wavelength dependent variations in the excitation radiant power this is called a corrected excitation spectrum.
See also: emission spectrum
Source:
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2241 (https://doi.org/10.1351/pac199668122223)
See also:
Orange Book, 2nd ed., p. 197 (https://media.iupac.org/publications/analytical_compendium/)