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首页> 外文期刊>The Journal of Chemical Physics >Pump-probe spectra of linear molecular aggregates: Effect of exciton-exciton interaction and higher molecular levels
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Pump-probe spectra of linear molecular aggregates: Effect of exciton-exciton interaction and higher molecular levels

机译：线性分子聚集体的泵浦-探针光谱：激子-激子相互作用和更高分子水平的影响

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The paper considers the differential pump-probe spectra due to excitons in linear molecular aggregates taking into account simultaneously effects of both exciton-exciton interaction and higher molecular levels. The theoretical analysis, carried out in terms of the Green function technique, provides analytical expressions for the line shape of the pump-probe spectrum valid for an arbitrary number N of molecules forming the aggregate. Furthermore, the theory can accommodate any number of molecular,states with higher energies. This includes, inter alia, the most common situation in which the higher lying states form a dense set of sublevels of electronic, vibrational, etc, origin. It has been demonstrated that incorporation of such higher molecular levels introduces widths to biexciton peaks formed below the two-exciton continuum. In addition, the indirect interaction between the excitons via the higher molecular levels can facilitate formation of a biexciton at lower than usual values of the direct exciton-exciton coupling gamma, in extreme cases even for negative gamma values characterizing repulsion rather than attraction between the excitons. On the other hand, in the region around the exciton band-edge, the differential spectrum can be described reasonably well in terms of the model of noninteracting excitons for a wide range of parameters of the system, subject to the replacement of an actual number of molecules per aggregate N by the effective one N-eff. The latter N-eff is shown to be influenced both by the direct coupling between the excitons and also by the indirect coupling via the higher molecular levels. (C) 1998 American Institute of Physics. [S0021-9606(98)70638-5]. [References: 51]
机译：本文考虑了线性分子聚集体中的激子引起的差分泵浦-探针谱，同时考虑了激子-激子相互作用和更高分子水平的影响。根据格林函数技术进行的理论分析为泵浦探针谱的线形提供了解析表达式，该表达式对于任意数量N的形成聚集体的分子均有效。此外，该理论可以容纳具有更高能量的任何数量的分子状态。除其他外，这包括最常见的情况，其中较高的躺卧状态形成了电子，振动等起源的密集的子级集合。已经证明掺入这种较高的分子水平会导致在两个激子连续峰以下形成的双激子峰的宽度增加。另外，激子之间通过较高分子水平的间接相互作用可以促进双激子的形成，其比直接激子-激子耦合伽马的通常值低，在极端情况下，甚至对于表征排斥力而不是激子之间的吸引力的负伽马值。另一方面，在激子带边缘周围的区域中，对于系统的各种参数，只要替换实际数量的激子，就可以根据非相互作用激子的模型合理地描述差分光谱。分子每聚集N时的有效分子数为N-eff。后者的N-eff既受激子之间的直接偶合影响，也受较高分子水平的间接偶合影响。 （C）1998美国物理研究所。 [S0021-9606（98）70638-5]。 [参考：51]

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