The Red-Shift Cascade: Investigations into the Concentration-Dependent Wavelength Shifts in Three-Dimensional Fluorescence Spectra of Petroleum Samples

Samples of motor oil and creosote are subjected to three-dimensional fluorescence spectroscopy to document the shifting of excitation/emission maxima as the solutions undergo serial dilutions. Effects such as self-quenching of individual polycyclic aromatic hydrocarbons (PAHs) and energy transfer between PAHs combine to produce large red-shifts in the resulting fluorescence emission spectra. The concentration-imposed complications are also demonstrated for several synthetic ternary PAH mixtures and a diesel residue mimic.