diffuse reflectance

symbol: $R$
synonyms: remission fraction, remittance
https://doi.org/10.1351/goldbook.08235
Diffuse reflected (remitted) radiant power (\(P_{\rm{rem}}\)) divided by incident radiant power (\(P_{0}\)). \(R = P_{\rm{rem}}/P_{0}\).
Notes:
  1. The sum of remittance, transmittance, and absorptance equals one.
  2. Some authors distinguish between remittance and diffuse reflectance by excluding specular reflection in the latter.
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 655 (https://doi.org/10.1515/pac-2019-0203)