Surface enrichment of soot particles in photoelectrically active trace species

Abstract

Combustion aerosols are examined by in situ photoelectron emission. The photoelectric yield Y is determined as a function of the particle size. For car exhaust, Y is proportional 1/R. This is consistent with the assumption that hydrocarbons exhibiting low photothresholds have been deposited on the surface of larger soot particles. Y then corresponds to the degree of surface enrichment in compounds of low photothreshold. For aerosols produced by incomplete combustion of butane, Y does not depend on the particle size, indicating a complete coverage of the surface. The surface material may confer high chemical activity to the particles although being present only as traces. © 1984.