Kong Jie, Huo Dayujia, Jie Jialong, Wu Yanzhen, Wan Yan, Song Yongbo, Zhou Meng
Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.
College of Chemistry, Beijing Normal University, Beijing 100875, China.
Nanoscale. 2021 Dec 2;13(46):19438-19445. doi: 10.1039/d1nr06208e.
The excited state dynamics of small-sized metal nanoclusters are dependent on their crystal structures, while the effect of the charge state remains largely unknown. Here, we report the influence of single electrons on the excited-state dynamics of non-superatom Au clusters by comparing the transient absorption isotropy and anisotropy dynamics of two rod-shaped Au nanoclusters protected by organic ligands. Two decay lifetimes (0.9 ps and 2.3 μs) can be identified in the excited state relaxation of Au rods, which are assigned to the internal conversion from a higher to lower excited state and the relaxation to the ground state, respectively. With the addition of one electron, an additional 660 ps decay is observed in Au, which should originate from the presence of a single electron occupied molecular orbital. Transient anisotropy measurements reveal a 500 ps rotational diffusion process in both the nanoclusters, while the initial dipole moment orientation is found to be highly dependent on the charge state. These results are of importance to understanding the effect of the charge state on the optical properties of metal nanoclusters.
小尺寸金属纳米团簇的激发态动力学取决于其晶体结构，而电荷态的影响在很大程度上仍不清楚。在此，我们通过比较两种由有机配体保护的棒状金纳米团簇的瞬态吸收各向同性和各向异性动力学，报告了单电子对非超原子金团簇激发态动力学的影响。在金棒的激发态弛豫过程中可以识别出两个衰减寿命（0.9皮秒和2.3微秒），它们分别对应于从较高激发态到较低激发态的内转换以及弛豫到基态。添加一个电子后，在金中观察到一个额外的660皮秒衰减，这应该源于单电子占据分子轨道的存在。瞬态各向异性测量揭示了两种纳米团簇中均存在一个500皮秒的旋转扩散过程，而初始偶极矩取向被发现高度依赖于电荷态。这些结果对于理解电荷态对金属纳米团簇光学性质的影响具有重要意义。
