亚甲基蓝分子团簇与双金属纳米结构的多模耦合效应  

Multimodal coupling effect between methylene blue molecular clusters and dual metal nanoparticles

作　　者：张攀 方德音 郝梦圆 王鹿霞[1] ZHANG Pan;FANG Deyin;HAO Mengyuan;WANG Luxia(Institute of Theoretical Physics,School of Mathematics and Physics,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学数理学院,理论物理研究所,北京100083

出　　处：《物理学报》2025年第6期220-231,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:21961132023)资助的课题.

摘　　要：基于亚甲基蓝(methylene Blue,MB)-银纳米腔体系的双拉比分裂实验,建立了MB分子团簇和双金属纳米粒子结构模型,在密度矩阵理论框架下,应用偶极近似方法,计算了MB分子团簇与双金属纳米粒子形成的杂化态的耦合动力学过程,研究了多激子态-等离激元相互作用下的多模耦合效应,得到了与实验定性一致的结果.通过短脉冲激发,在更大的激发频域下研究激子态和等离激元的耦合态.探讨了激子退相干速率和分子间距离对耦合过程的影响、分子与等离激元的耦合强度随激子退相干时间缩短而增强的现象,由于团簇内离域激子与等离激元耦合相互作用,复合体系内可以产生更多杂化能级,使得光学响应峰发生相应变化.通过对分子团簇与金属纳米结构的多模耦合的机理研究,为设计高效光捕获和转换材料提供了理论依据和思路.Methylene blue(MB),as an organic dye,exhibits rich photophysical properties when interacting with metal nanoparticles.Based on the double Rabi splitting experiment of MB molecular clusters and dual metal nanoparticles in a silver nanocavity,a cluster model composed of MB molecular monomers and dimers is developed and placed in a nanocavity environment consisting of two metal nanoparticles in this work.The density matrix theory framework combined with dipole approximation is used to calculate the coupling dynamics of the hybrid state formed between MB molecular clusters and dual metal nanoparticles.The semiclassical model is used to deal with the coupling of external fieldsand molecules and plasmons,and the multimode coupling effect caused by the interaction between multi-exciton states and plasmons is discussed.The results are qualitatively consistent with experimental results.The research results show that under the excitation of strong short pulse fields,single-mode coupling occurs mainly between MB monomers and nanocavities,forming new hybrid states.When the molecular cluster is composed of a mixture of monomers and dimers,it forms a multi-mode coupling state with the nanocavity.As the pulse width decreases,more exciton states and plasmon states are activated,which not only enhances the coupling effect but also further expands the excitation range of excitons.The effects of exciton decoherence rate and intermolecular distance on the coupling process are explored.The results show that the coupling strength increases with the exciton decoherence rate decreasing,that is,the longer the exciton decoherence time,the greater the coupling strength will be.This is because a longer decoherence time means that the exciton state has a longer lifetime and can more effectively couple with the plasmonic state.Meanwhile,molecular spacing is also an important factor affecting coupling behaviors.When the intermolecular distance is small,the coupling between excitons is enhanced,which leads to an increase of the splitting of hyb

关 键 词：亚甲基蓝分子团簇 金属纳米粒子 光学响应 多模耦合 

分 类 号：TB3[一般工业技术—材料科学与工程]