Davydov Splitting in Squaraine Dimers
Davydov Splitting in Squaraine Dimers
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DOI：
10.1021/acs.jpcc.9b05297
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发表时间：
2019-07
期刊：
影响因子：
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通讯作者：
Chuwei Zhong;D. Bialas;C. Collison;F. Spano
中科院分区：
文献类型：
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作者：
Chuwei Zhong;D. Bialas;C. Collison;F. Spano
采用施主-受主-施主（D-A-D）生色团的基本态模型（ESM）研究了中心对称和非中心对称方酸分子组成的分子二聚体的吸收和光致发光（PL）。谱线的形状和位移相对于单体光谱是由于一个有趣的相互作用的三个中心的电荷分布负责地面和激发态（永久）的偶极子和四极矩和两个中心的电荷分布负责过渡偶极矩。的达维多夫分裂是敏感的，只有（扩展）过渡偶极之间的相互作用，而永久偶极-偶极和四极-四极相互作用的影响的两个达维多夫组件的中点频率，导致一个一般不对称分裂相对于峰值单体跃迁频率。该理论准确地再现了稳态吸收和PL线的形状最近获得的共价键结合方酸二聚体。ESM还预测了一种极端类型的非Kasha行为，其中两个Davydov分量在单体跃迁频率以上蓝移。
The essential states model (ESM) for donor–acceptor–donor (D–A–D) chromophores is used to explore absorption and photoluminescence (PL) in molecular dimers composed of centrosymmetric and non-centrosymmetric squaraine molecules. The spectral line shapes and shifts relative to the monomer spectrum are due to an interesting interplay between three-center charge distributions responsible for ground- and excited-state (permanent) dipole and quadrupole moments and two-center charge distributions responsible for transition dipole moments. The Davydov splitting is sensitive only to the interactions between the (extended) transition dipoles , whereas the permanent dipole-dipole and quadruple-quadrupole interactions impact the midpoint frequency of the two Davydov components, leading to a generally asymmetric splitting relative to the peak monomer transition frequency. The theory accurately reproduces the steady-state absorption and PL line shapes recently obtained for covalently bound squaraine dimers. The ESM also predicts an extreme type of non-Kasha behavior, where both Davydov components are blue-shifted above the monomer transition frequency.