Nakai Katsunori, Sahnoun Riadh, Kato Tsuyoshi, Kono Hirohiko, Fujimura Yuichi
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
J Phys Chem B. 2005 Jul 28;109(29):13921-7. doi: 10.1021/jp050720y.
By using time-dependent density functional theory, we calculated the transition energies of a zinc porphyrin monomer and its meso-meso-linked arrays. In line with the prediction of the molecular exciton model, the calculated splitting energy of the Soret band increased as the number of linked porphyrins increased. We then examined how the transition energies of the dimer array were shifted by an applied electric field. For reproduction of an electroabsorption spectrum (EA), i.e., the field-induced change in absorption intensity, a model Hamiltonian constructed from five states is proposed. It is concluded for the dimer that the field-induced coupling between the lower-energy Soret band Se and the lower-lying ionic character (charge-transfer) states is responsible for the experimentally observed blue shift of Se as well as the second-derivative profile in the EA spectrum.
通过使用含时密度泛函理论，我们计算了锌卟啉单体及其间位-间位连接阵列的跃迁能。与分子激子模型的预测一致，计算得到的Soret带的分裂能随着连接卟啉数量的增加而增大。然后，我们研究了施加电场如何使二聚体阵列的跃迁能发生移动。为了再现电吸收光谱（EA），即场诱导的吸收强度变化，提出了一个由五个态构建的模型哈密顿量。对于二聚体得出的结论是，低能Soret带Se与较低的离子特性（电荷转移）态之间的场诱导耦合是导致实验观察到的Se蓝移以及EA光谱中的二阶导数谱形的原因。
