and
).
Also used for devices producing an electrical signal proportional to the photon flux absorbed in a medium.
Source:
PAC, 1996, 68, 2223
(Glossary of terms used in photochemistry (IUPAC Recommendations 1996))
on page 2267
PAC, 1984, 56, 231
(Nomenclature, symbols, units and their usage in spectrochemical analysis-Part VI:
molecular luminescence spectroscopy)
on page 238