External heavy-atom effect on the room-temperature luminescence of adsorbed dyes
External heavy-atom effect on the room-temperature luminescence of adsorbed dyes
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外部重原子对吸附染料室温发光的影响
DOI：
10.1021/j100536a017
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发表时间：
1977
期刊：
影响因子：
--
通讯作者：
P. Seybold
中科院分区：
文献类型：
--
作者：
W. White;P. Seybold
研究了添加的碱金属卤化物盐对吸附在滤纸上的2-萘磺酸盐的室温荧光和磷光的影响。观察到正常的外部重原子对发光的影响，按 NaF< NaCl< NaBr< Nal 的顺序强烈增加。荧光猝灭对扰动浓度的依赖性可以通过 Perrin 方程的修改版本来描述。外部重原子增加的辐射三重态衰变常数 kp 比竞争的非辐射常数 k^, 更多。结果与扰动分子和染料分子之间的交换相互作用模型一致，其中 S*-* T 跃迁强度是从扰动卤化物离子的电子跃迁借用的，但不能完全排除电荷转移的参与。Kasha1 证明高原子数的环境原子（“重原子”）可以改变分子自旋禁止跃迁的速率，至今已有四分之一个世纪了。这种外部重原子效应与内部重原子效应不同，McClure 早先证明了这一点，2, 3，其中重原子与受影响的芳香族化合物化学键合。随后大量的实验和理论研究致力于这个主题，4" 25 证实了最初的假设1，即该效应取决于自旋轨道耦合，并描述了重原子带来的光谱变化。尽管受到了仔细审查，外部重原子效应的许多重要特征仍然模糊或令人困惑。关于芳香族化合物和重原子扰动物种之间的基本相互作用，一些作者声称电荷转移复合物6" 8， 11,158 人出席，而其他人则支持交换互动。 9、13、14、23 激基复合物有时也有
The effect of added alkali halide salts on the room-temperature fluorescence and phosphorescence of 2-naphthalenesulfonate adsorbed on filter paper has been examined. A normal external heavy atom effect on luminescence is observed, increasing strongly in the order NaF< NaCl< NaBr< Nal. The dependence of fluorescence quenching on perturber concentration can be describedby a modified version of the Perrin equation. External heavy atoms increase the radiative triplet decay constant kp more than the competing nonradiative constant k^,. The results are consistent with an exchange interaction model between perturber anddye molecule, in which S*-* T transition intensity is borrowed from electronic transistions of the perturbing halide ion, but charge-transfer involvement cannot be completely ruled out.It is now a quarter century since Kasha1 showed that environmental atoms of high atom number (“heavy atoms”) can alter the rates of molecular spin-forbidden transitions. This external heavy-atom, effect is distinguished from the internal heavy-atom effect, earlier demonstrated by McClure, 2, 3 wherein heavy atoms are chemically bonded to the affected aromatic compound. A large numberof subsequent experimental and theoretical studies have been devoted to this topic, 4" 25 confirming the original hypothesis1 that the effect depends on spin-orbit coupling and describing the spectroscopic alterations brought on by the heavy atoms. Despite the scrutiny it has received, many important features of the external heavy-atom effect remain obscure or confusing. Regarding the fundamental interaction between the aromatic compound and the heavy-atom perturbing species, some authors claim that charge-transfer complexes6" 8, 11,158 are present, whereas others favor ex-change interactions. 9, 13, 14, 23 Exciplexes have also sometimes