Chimeric behavior of excited thioxanthone in protic solvents: I. Experiments.
Chimeric behavior of excited thioxanthone in protic solvents: I. Experiments.
复制标题
DOI：
10.1021/jp5099393
复制
发表时间：
2014-12
期刊：
影响因子：
--
通讯作者：
Torben Villnow;G. Ryseck;Vidisha Rai-Constapel;C. Marian;P. Gilch
中科院分区：
文献类型：
--
作者：
Torben Villnow;G. Ryseck;Vidisha Rai-Constapel;C. Marian;P. Gilch
通过时间分辨荧光和吸收光谱研究了溶解在甲醇 (MeOH) 和 2,2,2,-三氟乙醇 (TFE) 中的噻吨酮 (TX) 的光物理学。光谱积分受激发射的振幅在 ∼5-10 ps 内丢失。这比化合物的荧光寿命（MeOH 为 2.7 ns，TFE 为 7.6 ns）短得多。振幅的初始减小归因于主激发 (1)ππ* 和三重态 (3)nπ* 态之间的可逆系间跨越。后者在能量上略高于前者（∼0.02 eV）。添加猝灭剂 1-甲基萘 (1-MN) 会降低荧光寿命并产生三重态激发的 1-MN，为单重态和三重态激发的平衡提供了进一步的证据。这两个态在纳秒时间尺度上的减少导致最低三重态（(3)ππ*态）的上升。温度依赖性将此归因于两个三重态之间激活的内部转换过程。从实验数据得出的动力学和能量参数将与随附论文中的量子化学结果进行比较 [Rai-Constapel, V., Villnow, T., Ryseck, G., Gilch, P. 和 Marian, C. M. J. Phys.化学。 2014 年，DOI：10.1021/jp5099415]。
The photophysics of thioxanthone (TX) dissolved in methanol (MeOH) and 2,2,2,-trifluoroethanol (TFE) was studied by time-resolved fluorescence and absorption spectroscopy. The spectrally integrated stimulated emission is seen to lose amplitude within ∼5-10 ps. This is much shorter than the fluorescence lifetimes of the compound (2.7 ns for MeOH and 7.6 ns for TFE). The initial reduction in amplitude is attributed to reversible intersystem crossing between the primarily excited (1)ππ* and a triplet (3)nπ* state. The latter one is energetically slightly (∼0.02 eV) above the former one. Addition of the quencher 1-methylnaphthalene (1-MN) reduces the fluorescence lifetime and yields triplet excited 1-MN, giving further evidence for the equilibrium of singlet and triplet excitations. The depopulation of these two states on the nanosecond time scale results in the rise of the lowest triplet state, a (3)ππ* state. Temperature dependencies attribute this to an activated internal conversion process between the two triplet states. Kinetic and energetic parameters derived from the experimental data will be compared with quantum chemical results in the accompanying paper [Rai-Constapel , V. , Villnow , T. , Ryseck , G. , Gilch , P. , and Marian , C. M. J. Phys. Chem. A 2014 , DOI: 10.1021/jp5099415].