specular reflectance (reflection factor), ρ 

in optical spectroscopy
https://doi.org/10.1351/goldbook.S05851
Radiant power specularly reflected from the surface of a system, Prefl, divided by the incident power, P0: ρ=PreflP0
Source:
PAC, 1985, 57, 105. (Names, symbols, definitions and units of quantities in optical spectroscopy (Recommendations 1984)) on page 115 [Terms] [Paper]
Citation: 'specular reflectance' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.S05851 RIS BibTex EndNote
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Last revised: February 24, 2014