Each 3D scan took approximately four hours to complete and consisted of 57 individual spectra. The advantage of a 3D plot is that all aspects of excitation and emission can be derived. Any of the 57 fluorescence emission spectra for a given excitation can be separated, and data for excitations not specifically analyzed can be interpolated. In addition, photoluminescence excitation (PLE) spectra for a given emission wavelength can be obtained to see the effect of excitation light frequency on fluorescence. Figure 3 illustrates these features in the anatomy of a 3D fluorescence spectrum.