Single scattering albedo - the ratio of scattering efficiency to total extinction efficiency (which is also termed "attenuance", a sum of scattering and absorption). Most often it is defined for small-particle scattering of electromagnetic waves. A single scattering albedo of unity implies that all particle extinction is due to scattering; conversely, a single scattering albedo of zero implies that all extinction is due to absorption.
For spherical particles one can calculate single scattering albedo from Mie theory and knowledge of bulk properties of material such as refractive index. For non-spherical particles one could use discrete dipole approximation or other methods of computational electromagnetics.