The following figures show the behaviour of the efficiency factors Q ext , Q sca , Q abs as well as albedo and asymmetry parameter g for porous particles. ... These optical characteristics are compared with results of Lorenz-Mie calculations for corresponding n -layered spheres. ... factors . Qext(x) . Qsca(x) . ... Qabs (x) . ... albedo (x) . ... Henning, Modelling the optical properties of composite and porous interstellar grains, Astronomy and Astrophysics , 429 , 371-381, 2005. ...