Many studies have been carried out on the measurements of luminescence yields as a function of the solute concentrations in aromatic solvents. Most of these have been done at moderate solute concentrations, between 0.1 and 20 g/l. The scope of this work was a study of the luminescence yield at low solute concentrations, down to 0.005 g/l. Only at these low concentrations is it possible to get information on other processes which might occur in the liquid scintillator solution system. Of particular interest is the measurement of the contribution to the luminescence yield of a possible radiative transfer process at low solute concentrations.