photon number, Np
Total number of photons calculated as Np = np.NA with Np the amount of photons in einsteins and NA the Avogadro constant.
Mathematical definition: Np = Q/hν for monochromatic radiation of frequency ν, with Q the @R05039@.
PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 396 (