Excimer/Exciplex Formation in van der Waals Dimers of Aromatic Molecules
Excimer/Exciplex Formation in van der Waals Dimers of Aromatic Molecules
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DOI：
10.1021/jp9537668
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发表时间：
1996-07
期刊：
影响因子：
--
通讯作者：
W. Yip;D. Levy
中科院分区：
文献类型：
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作者：
W. Yip;D. Levy
在超音速射流中研究了苯并呋喃、二苯并呋喃和芴之间的货车范德华二聚物。这些示出了在激发到它们的局部激发态之后的红移的激基缔合物/激基复合物发射。二苯并呋喃二聚体从其零点能级形成激基缔合物，而二苯并呋喃-苯并呋喃和芴-苯并呋喃二聚体需要适量的过量振动能来形成激基缔合物。二苯并呋喃-芴中激基复合物的形成是从光谱增宽推断的。准分子/激基复合物的形成归因于强混合的电荷转移状态与激子状态。电荷转移态在其平衡几何结构下具有足够低的能量来混合，但这需要从局部激发态的平衡几何结构的几何结构的大的变化。在绝热势面中，在局部激发态的最小值和激基复合物态的最小值之间存在势垒。平衡几何形状的差异越大，该势垒越大。
Van der Waals dimers between benzofuran, dibenzofuran, and fluorene were studied in a supersonic jet. These show red-shifted excimer/exciplex emission following excitation to their locally excited states. The dibenzofuran dimer forms an excimer from its zero-point level, while the dibenzofuran−benzofuran and fluorene−benzofuran dimers require a moderate amount of excess vibrational energy for excimer formation. Exciplex formation in dibenzofuran−fluorene was inferred from spectral broadening. Excimer/exciplex formation was attributed to strong mixing of a charge transfer state with the exciton state. The charge transfer state has a low enough energy at its equilibrium geometry to mix, but this requires a large change in geometry from the equilibrium geometry of the locally excited state. There is a barrier in the adiabatic potential surface between the minima of the locally excited state and the excimer/exciplex state. This barrier is larger for greater differences in equilibrium geometry.