Comisión Nacional de Energía Atómica (CNEA), CONICET, Gerencia Química, Centro Atómico Constituyentes, Av. Gral. Paz 1499, B1650KNA, San Martín, Buenos Aires, Argentina.
Methods Appl Fluoresc. 2017 Aug 17;5(3):034001. doi: 10.1088/2050-6120/aa72a9.
In the present work we show that a recent methodology developed by us to acquire emission spectra and fluorescence quantum yields of highly absorbing samples in transmission configuration, constitutes a very simple and robust alternative to determine self-quenching constants, K . We measured the absorption and the steady-state emission spectra of quinine bisulphate, QBS, solutions ranging between 1.5 × 10 and 1.5 × 10 M. From these data, we calculated the expected emission spectra, affected by re-absorption, for all QBS concentrations. For higher concentrations, the re-absorption in the excitation/detection direction reaches values up to 6% of the total emitted intensity. The K of the dye was re-evaluated from the concentration dependence of the quotients between the calculated and the experimental integrated emission spectra. The obtained value, K = 18.4 ± 0.1 M, shows no significant differences with those obtained from steady-state and average lifetimes by other authors, pointing out the diffusional nature of the self-quenching phenomenon. The present work helps clarify some ambiguous aspects concerning the photophysics of QBS, stressing that re-absorption phenomena must be considered in QBS concentrated solutions for accuracy measurements.
在本工作中，我们展示了我们最近开发的一种用于在透射配置中获取高吸收样品的发射光谱和荧光量子产率的方法，这是一种非常简单和稳健的替代方法，可以确定自猝灭常数 K 。我们测量了硫酸奎宁双盐（QBS）溶液的吸收和稳态发射光谱，浓度范围在 1.5×10 和 1.5×10 M 之间。根据这些数据，我们计算了所有 QBS 浓度下受再吸收影响的预期发射光谱。对于较高的浓度，激发/检测方向的再吸收达到了总发射强度的 6%。从浓度对计算和实验积分发射光谱之间比值的依赖关系中，重新评估了染料的 K 。得到的值 K = 18.4 ± 0.1 M 与其他作者通过稳态和平均寿命获得的值没有显著差异，这表明自猝灭现象具有扩散性质。本工作有助于澄清有关 QBS 光物理的一些模糊方面，强调在 QBS 浓溶液中必须考虑再吸收现象，以进行准确测量。
