FLUORESCENCE YIELDS OF AROMATIC COMPOUNDS

Values of fluorescence yields for 18 compounds in solution at 23° are reported and they are compared with previous literature values. Modifications of the technique of Weber and Teale for measurement of fluorescence yields are described. Fluorescein in 0.1 N NaOH and anthracene in ethanol are the best fluorescence standards on the basis of agreement of fluorescence yields with other work. The use of quinine as a fluorescence standard is complicated by variation of its fluorescence yield with H2SO4 concentration and the excitation wavelength. Several other compounds, including chrysene, show no variation of fluorescence yield with a change of excitation wavelength. Radiative lifetimes estimated from integrated absorption spectra are found to be consistently shorter than the radiative lifetimes estimated from fluorescence yields and lifetimes. The fluorescence yields of pyrene-d10 and anthracene-d10 in ethanol are significantly lower than those of corresponding solutions of pyrene-h10 and anthracene-h10, respectively. No significant effect of compound deuteration upon the fluorescence yields of seven other compounds is found.