摘要
掺杂金属纳米团簇的光学性质因为其在生物探针和光催化等方向的应用受到广泛关注.MAu_(24)(SR)_(18)团簇的光致发光和激发态过程复杂,其机制尚不清楚.本文利用超快光谱探究了两种掺杂金属纳米团簇MAu_(24)(SR)_(18)(M=Pd,Pt,SR为苯乙硫醇)的激子和相干振动动力学.与未掺杂的Au_(25)(SR)_(18)团簇相比,Pd和Pt掺杂导致激子寿命显著降低几个数量级.研究发现PtAu_(24)(5 ps)和PdAu_(24)(30 ps)超短的激子寿命来源于超小的能隙(Eg=0.3eV).在两个掺杂金属团簇中,都观测到显著的来自金核的相干振荡(2.4 THz),表明这些相干振荡在超短激子寿命下依然能稳定存在.理解掺杂金属纳米团簇的激子和振动动力学将为设计这些类似分子的纳米材料提供新思路.
The optical properties of doped metal nanoclusters(NCs)have stimulated great research interests because of their applications in biosensing and photocatalysis.The photoluminescence and excited state dynamics of MAu24(SR)18 are complicated and the detailed mechanism has not been fully understood.Here,we investigate the exciton and vibrational dynamics of two doped NCs MAu_(24)(SR)_(18)(M=Pd,Pt;SR stands for phenylethanethiolate)by ultrafast spectroscopy.In contrast to the parent Au_(25)(SR)_(18)NCs,Pd and Pt doping significantly reduce the exciton lifetime by several orders of magnitude.We find that the ultrashort exciton lifetimes of PtAu_(24)(5 ps)and PdAu_(24)(30 ps)are ascribed to the ultrasmall energy gap(E_(g)=0.3 eV).In both two doped NCs,we observe significant coherent vibrations(2.4 THz)that arise from the metal core,which indicates these oscillations can survive regardless of the short exciton lifetime.Unravelling the effect of foreign atom doping on the exciton and vibrational dynamics of metal NCs will provide new insight into their optical properties and help designing these molecular-like nanostructures for specific applications.
作者
吴燕珍
刘旭
孔洁
张伟
祝艳
周蒙
Yanzhen Wu;Xu Liu;Jie Kong;Wei Zhang;Yan Zhu;Meng Zhou(Hefei National Laboratory for Physical Sciences at the Microscale,University of Science and Technology of China,Hefei 230026,China;Key Lab of Mesoscopic Chemistry of MOE and Jiangsu Key Lab of Vehicle Emissions Control,School of Chemistry and Chemical Engineering,Nanjing University,Nanjing 210093,China)
基金
supported by the National Natural Science Foundation of China(No.22273095).
关键词
超快光谱
纳米团簇
激发态动力学
Ultrafast spectroscopy
Nanocluster
Exciton dynamics
