Origin of the enhancement of the second hyperpolarizability of singlet diradical systems with intermediate diradical character.
Origin of the enhancement of the second hyperpolarizability of singlet diradical systems with intermediate diradical character.
复制标题
DOI：
10.1063/1.2213974
复制
发表时间：
2006-08
期刊：
影响因子：
--
通讯作者：
M. Nakano;R. Kishi;Suguru Ohta;A. Takebe;Hideaki Takahashi;S. Furukawa;T. Kubo;Y. Morita;K. Nakasuji;K. Yamaguchi;K. Kamada;K. Ohta;B. Champagne;E. Botek
中科院分区：
文献类型：
--
作者：
M. Nakano;R. Kishi;Suguru Ohta;A. Takebe;Hideaki Takahashi;S. Furukawa;T. Kubo;Y. Morita;K. Nakasuji;K. Yamaguchi;K. Kamada;K. Ohta;B. Champagne;E. Botek
利用具有不同双自由基性质的最简单双自由基分子模型，即键解离下的H2，根据伽马的摄动公式，阐明了中性单线态双自由基体系二阶超极化率（γ）的双自由基性质依赖的来源。伽马在中间双激发态特征区增强的原因是随着双激发态特征的增加，第一激发态和第二激发态之间的跃迁矩增大，基态和第一激发态之间的跃迁矩减小。这一特征证实了具有中间双自由基性质的开壳单重态共轭分子构成了一类新的三阶非线性光学系统，其伽马值不仅可以由共轭长度控制，还可以由双自由基性质控制。
The origin of the diradical character dependence of the second hyperpolarizability (gamma) of neutral singlet diradical systems is clarified based on the perturbation formula of gamma using the simplest diradical molecular model with different diradical characters, i.e., H2 under bond dissociation. The enhancement of gamma in the intermediate diradical character region turns out to originate from the increasing magnitude of the transition moment between the first and second excited states and the decrease of that between the ground and first excited states, respectively, with the increase in diradical character. This feature confirms that open-shell singlet conjugated molecules with intermediate diradical characters constitute a new class of third-order nonlinear optical systems, whose gamma values can be controlled by the diradical character in addition to the conjugation length.