title: A Study of Excitation Delocalization/Localization in Multibranched Chromophores by Using Fluorescence Excitation Anisotropy Spectroscopy.
abstract: We describe a simple approach to study the excitation localization/delocalization in multibranched chromophores by using fluorescence excitation anisotropy spectroscopy at room temperature. As examples, the electronic excitations in three different multibranched chromophores (dimers) are investigated. For a weakly coupled dimer, fluorescence anisotropy is independent of excitation wavelength, due to localized excitation as well as the degenerate electronic excited states. In contrast, in the case of a strongly coupled dimer, owing to excitonic splitting, a redistribution of the excitation energy is demonstrated by the dependence of anisotropy spectra on the excitation wavelength, which leads to significant deviation from the anisotropy signal of localized excitation. In particular, based on the law of additivity for anisotropy, the degree of delocalized excitation can be simply estimated for a given dimer.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences Department, Bejing, 100190, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences Department, Bejing, 100190, China.
authors.forename: Guiying
authors.initials: G
authors.lastname: He
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences Department, Bejing, 100190, China.
authors.forename: Xian
authors.initials: X
authors.lastname: Wang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences Department, Bejing, 100190, China.
authors.forename: Qianjin
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences Department, Bejing, 100190, China. andong@iccas.ac.cn.
authors.forename: Yingli
authors.initials: Y
authors.lastname: Niu
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences Department, Bejing, 100190, China. ylniu@iccas.ac.cn.
authors.forename: Andong
authors.initials: A
authors.lastname: Xia
keywords: ab initio calculations; chromophores; delocalization; energy transfer; fluorescence