We report an experimental and theoretical investigation of the electronic and optical properties of a series of icosahedral Au₁₃ nanoclusters, protected using different halogen ligands (Cl, Br, and I), as well as 1,2-bis(diphenylphosphino)ethane (dppe) ligands. All three clusters are comprised of the same Au₁₃ kernel with two halogens coordinated to the poles of the icosahedral cluster along with five dppe ligands. UV-vis absorption spectra indicate a systematic red shift from Cl to Br to I, as well as a sudden enhancement of the second excitonic peak for the I-coordinated cluster. Density functional theory (DFT) calculations suggest that all clusters possess a wide HOMO–LUMO energy gap of ∼1.79 eV and are used to assign the first two excitonic bands. Frontier orbital analyses reveal several HOMO → LUMO transitions involving halogen-to-metal charge transfers. For the I-coordinated cluster, more complicated I-to-metal charge transfers give rise to different excitation features observed experimentally. The current findings show that halogen ligands play important roles in the electronic structures of gold clusters and can be utilized to tune the optical properties of the clusters.

中文翻译：

---

卤素对 Au13 纳米团簇电子和光学性质的影响

我们报告了一系列二十面体 Au ₁₃纳米团簇的电子和光学性质的实验和理论研究，这些纳米团簇使用不同的卤素配体（Cl、Br 和 I）以及 1,2-双（二苯基膦基）乙烷（dppe ) 配体。所有三个集群都由相同的 Au _13组成内核具有两个卤素与二十面体簇的两极配体以及五个 dppe 配体。UV-vis 吸收光谱表明从 Cl 到 Br 到 I 的系统性红移，以及 I 配位簇的第二个激子峰的突然增强。密度泛函理论 (DFT) 计算表明，所有簇都具有约 1.79 eV 的宽 HOMO-LUMO 能隙，并用于分配前两个激子带。前沿轨道分析揭示了几个涉及卤素到金属电荷转移的 HOMO → LUMO 跃迁。对于 I 配位的簇，更复杂的 I 到金属的电荷转移会产生实验观察到的不同激发特征。