Rich and discrete energy states in gold nanoclusters enable different combinations of electronic transitions and correspondingly electrochemical and optical properties for a variety of applications. The impacts on those electronic transitions by the emergence and magnitude/alignment of a band gap and by the contributions from different atomic/molecular orbitals require further study. Au nanoclusters with 130 core Au atoms are of interest in this report because they are at the transition size regime where a small yet well-defined band gap can be resolved along with continuous quantized frontier core orbitals. Here, electrochemical analysis is combined with UV–vis–near infrared optical measurements to unveil previously unresolved electronic transitions. Finite changes in the steady-state optical absorption spectrum are captured by spectroelectrochemistry when the Au nanoclusters are charged to different states via electrolysis. Multiple previously unresolved peaks and valleys as well as isosbestic “points/regions” are observed in the differential spectrum. The detailed spectral features are explained by the respective electronic transitions to those affected energy states. Key features are also well correlated with ultrafast absorption analysis which provides additional insights, such as the lifetime of the corresponding transitions. The experimentally measured energy states and transitions could serve as references for future theoretical study to learn the respective contributions from different atomic orbitals and, importantly, to explore routes to enhance or suppress certain transition so as to modulate the corresponding electrochemical and optical properties for better applications.

中文翻译：

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光谱电化学和超快光谱技术在高度对称的Au ₁₃₀纳米团簇中的电子跃迁

金纳米团簇中的丰富和离散的能态使电子跃迁的不同组合以及相应的电化学和光学特性可用于多种应用。带隙的出现和幅度/排列以及不同原子/分子轨道的贡献对这些电子跃迁的影响需要进一步研究。本报告中关注具有130个核心Au原子的Au纳米团簇，因为它们处于过渡尺寸范围，可以解决一个小而界限分明的带隙以及连续量化的前沿核心轨道。在这里，电化学分析与近紫外可见光光学测量相结合，揭示了以前未解决的电子跃迁。当金纳米团簇通过电解被充电到不同的状态时，通过光谱电化学捕获稳态光吸收光谱中的有限变化。在微分光谱中观察到多个先前未解决的峰和谷以及同质的“点/区域”。详细的光谱特征由到那些受影响的能量状态的相应电子跃迁解释。关键特征还与超快速吸收分析紧密相关，超吸收分析提供了更多见解，例如相应跃迁的寿命。实验测得的能态和跃迁可以作为未来理论研究的参考，以学习不同原子轨道的各自贡献，重要的是，