Fluorescence of the hydrophobic acid fraction (HPOA) of Suwannee River natural organic matter and Tb³⁺ excitation spectra were measured in tandem using the instantaneous and time-resolved emission modes. The intensity of HPOA fluorescence decreased in the presence of Tb³⁺, while the intensity of the emission from Tb³⁺ cations bound by HPOA increased by up to several orders of magnitude due to energy transfer (ET) from HPOA to Tb³⁺ ions. To determine intrinsic ET and fluorescence quenching (FQ) coefficients, NICA–Donnan modeling was carried. It showed that phenolic groups in HPOA dominated both the ET and FQ processes and that the binding of Tb³⁺ by HPOA could be described using the non-ideality parameter n_Tb, median binding constant log \(\tilde{K}_{\text{Tb}}\) for the phenolic sites and intrinsic ET and FQ coefficients (denoted as η_TbΦ and α_TbΦ), and were 0.48, 8.5, 1385 and 0.12, respectively. The high value of the energy transfer coefficient of Tb³⁺ ions bound by the phenolic groups in HPOA is indicative of both the match between the electronic levels of the donor and acceptor, and the short distance between them. The deviation of the data of Nica–Donnan modeling of the ET and FQ dependence of versus [Tb]_total for a 1.0 M ionic strength highlights the need to quantify the distribution of donor–acceptor distances in HPOA molecules in more detail.

中文翻译：

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Ter离子与腐植酸相互作用的荧光猝灭和能量转移现象

使用瞬时和时间分辨发射模式，串联测定了苏万尼河天然有机物的疏水酸级分（HPOA）的荧光和Tb ³⁺激发光谱。在存在Tb ³⁺的情况下，HPOA荧光的强度降低，而由于HPOA向Tb ³⁺离子的能量转移（ET），HPOA结合的Tb ³⁺阳离子的发射强度增加了几个数量级。。为了确定内在的ET和荧光猝灭（FQ）系数，进行了NICA-Donnan建模。结果表明，HPOA中的酚基在ET和FQ过程中均占主导地位，HPOA对Tb ³⁺的结合可使用非理想参数描述Ñ_铽，中值的结合常数log \（\代字号{K} _ {\文本{铽}} \）为酚位点和固有ET和FQ系数（表示为η _TbΦ和α _TbΦ），和分别为0.48，8.5， 1385和0.12。HPOA中酚基结合的Tb ³⁺离子的能量转移系数很高，既表明了供体和受体电子能级之间的匹配，也表明它们之间的距离很短。与[TB]的ET及FQ依赖NICA-唐南建模的数据的偏差_总为1.0M的离子强度的亮点需要量化更详细供体-受体距离在HPOA分子的分布。