Steady-state absorption and emission spectra were recorded using a Cary 100 and Cary Eclipse spectrometer, respectively. Excitation and emission spectra were obtained using a PMT voltage of 800 V with 5 nm slit widths and a scan rate of 20 nm/min. Solutions for emission and excitation spectra were prepared with an optical density of ~0.18 at excitation wavelengths of 255, and 267 nm (Figures and). The fluorescence spectra were corrected for Raman emission of the solvent and for the lamp intensity at each respective wavelength. The fluorescence quantum yield was calculated following equation 1: