The fluorescence decay times and quantum efficiencies of 1,4,5,8-naphthalisoimides

Abstract Presented herein are the luminescence properties of several 1,4,5,8- polinahthalisoimides. The luminescence decay curves after deconvolution exhibit three decay times: τ 1 , τ 2 , and τ 3 .The luminescence lifetimes change along with the growth of excitation energy, as well as the contribution of each luminescence decay mechanism ( A 1 , A 2 , and A 3 ). The manner of change is distinct for one sample, namely, the pure E-isomer, in comparison to the others. The radiative deexcitation coupled with radiationless vibrational energy transfer to other luminescence centers, mainly other isomer units, is discussed as a possible deexcitation mechanism of fluorescence. The Kasha–Vavilov empirical rule is not fulfilled for the studied samples, as the luminescence quantum efficiency ( Φ F ) distinctly depends on the excitation wavelength ( λ exc ). The quantum yield of one sample (about 63% of Z-isomer) is quite high, at 1%.