Reversible Excited-State Proton Geminate Recombination: Revisited.
Reversible Excited-State Proton Geminate Recombination: Revisited.
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可逆激发态质子对复合：重新审视。
DOI：
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发表时间：
2016
影响因子：
3.3
通讯作者：
D. Huppert
中科院分区：
文献类型：
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作者：
R. Simkovitch;D. Pines;Noam Agmon;E. Pines;D. Huppert
大约三十年前，Pines和Huppert发现，激发态质子从光酸(8-羟基-1，3，6-三磺酸)转移到水中之后，质子会发生有效的扩散辅助的可逆双酸盐复合。为了模拟该反应，Pines、Huppert和Agmon使用了适用于可逆接触反应动力学的边界条件的德拜-斯莫卢乔夫斯基方程。该反应模型已成功地用于HPTS和几种常用光酸的时间分辨荧光实验数据的定量拟合。这个反应的可逆性的结果是光酸荧光信号的一个明显的长时间尾巴，服从(寿命校正后)t-3/2幂定律渐近性。最近，Lawler和Fayer报道，在散体水中，观测到的HPTS长时间荧光尾巴的幂规律衰减率为-1.1，而不是球对称扩散模型所预期的-1.5。在目前的研究中，我们重申了我们之前关于HPTS荧光的幂定律行为的报道。我们还证明了分子水平的复杂性，如球对称性的偏离、转动动力学、竞争质子与HPTS的磺酸盐部分的结合、与距离有关的扩散系数和质子的初始起点，只在中间时间影响观察到的动力学，而不是在渐近较长的时间影响。理论上，我们用对数导数的极值个数来分析再结合动力学，显示出对接近渐近线的方向(无论是从上到下)的微妙影响，这一点也得到了实验的证实。
About three decades ago, Pines and Huppert found that the excited-state proton transfer to water from a photoacid (8-hydroxy-1,3,6-pyrene trisulfonate (HPTS)) is followed by an efficient diffusion-assisted reversible geminate-recombination of the proton. To model the reaction, Pines, Huppert, and Agmon used the Debye-Smoluchowski equation with boundary conditions appropriate for reversible contact reaction kinetics. This reaction model has been used successfully to quantitatively fit the experimental data of the time-resolved fluorescence of HPTS and several commonly used photoacids. A consequence of the reversibility of this reaction is an apparent long-time tail of the photoacid fluorescence signal, obeying (after lifetime correction) a t-3/2 power law asymptotics. Recently, Lawler and Fayer reported that in bulk water the observed power-law decay of the long-time fluorescence tail of HPTS is -1.1 rather than -1.5, as expected from the spherically symmetric diffusion model. In the current study, we reaffirm our previous reports of the power-law behavior of HPTS fluorescence. We also demonstrate that molecular-level complications such as the deviation from spherical symmetry, rotational dynamics, competitive proton binding to the sulfonate moieties of HPTS, distance-dependent diffusion coefficient, and the initial starting point of the proton can affect the observed kinetics only at intermediate times, but not at asymptotically long times. Theoretically, we analyze the rebinding kinetics in terms of the number of extrema of the logarithmic derivative, showing subtle effects on the direction of approach to the asymptotic line (whether from above or below), which also appears to be corroborated experimentally.
影响因子：
62.1
作者：
Agmon N;Bakker HJ;Campen RK;Henchman RH;Pohl P;Roke S;Thämer M;Hassanali A
通讯作者：
Hassanali A