Molecules with higher absorption and fluorescence energies are not excited and therefore have no contribution to the overall spectrum. Experimental results show that when shifting the excitation wavelength from 400 nm to 300 nm, the peak of the overall fluorescence spectrum of dilute asphaltene solution shifted from 440 nm (2.82 eV) to 360 nm (3.44 eV). The latter value is consistent with the calculated monomer fluorescence energy distribution.