When the sample is excited at either 325 nm or 370 nm, it yields broadband emissions at 650 nm, as illustrated in Figure . The excitation spectra monitored at 650 nm emission reveal that the photoluminescence arises most strongly from excitation from 3.2 to 4.1 eV (390 nm to 300 nm) light, with maxima occurring at 3.42 eV and 3.81 eV (362 nm and 325 nm). Lower energy light (e.g., 450 nm) also produces luminescence, but with a slightly blue-shifted spectrum and significantly lower intensity (Figure ). At 450 nm excitation, emission at 590 nm and 650 nm are observed but show very dim luminescence. The photoluminescence emission spectra obtained from excitations at 325 nm (3.81 eV) and 362 nm (3.42 eV) vs. 450 nm (2.76 eV) exhibit FWHM of 127 nm vs 174 nm, respectively. A full two-dimensional analysis of the excitation and emission spectra is provided in Figure ) eV (650 nm) independent of excitation wavelength. There is also a weak emission spectrum with a blue-shifted spectral weighting when excited with 450 nm light (green solid line). The excitation spectrum (dashed blue line) monitoring emission at 650 nm reveals two peaks at 325 nm (3.81 eV) and 370 nm (3.42 eV). All emission spectra are normalized to the data collected with 325 nm excitation; the emission spectrum collected with 450 nm excitation is multiplied by 20 for clarity.