The transition between plasmon resonance and photoluminescence in coinage metal and alloy nanoclusters (NC) is controlled by surface charge, core composition, and surface ligand type

从等离子体共振纳米粒子到金中的光致发光纳米团簇（NC）的过渡状态是在2-3纳米的尺寸上，其中这两种光学特征都不明显，仍然知之甚少。之前关于该主题的所有研究都集中在金属有机NC上，并以有机配体为上限，主要讨论粒径效应。然而，这种现象在多大程度上还受以下因素的支配：1)团簇中价电子的数量，2)贡献轨道的能量，或3)电子系统的极化率，人们仍然知之甚少。因此，由激光在液体中破碎而得到的无配体、完全无机的胶体NC是理想的模型材料。我们将阐明电子注入剂和电子抽吸剂如何影响过渡机制，区分A)离子的弱电荷转移效应B)来自富电子载体（如石墨烯）的强但离域的电荷转移，以及C)来自共价结合（Au-S）有机配体的强，局部但矛盾的效应。此外，在由Au、Ag和Cu组成的同源铸造金属NC系列中，包括具有固溶体和分离金属芯超微结构的AgAu和CuAu合金NC，其带隙能和极化率等元素特征也会发生变化。我们将研究金与另一种具有不同轨道能量和极化率的铸币金属掺杂如何影响跃迁状态，以及它与摩尔分数和元素混合的关系。

The transition regime from plasmon resonant nanoparticles to photoluminescent nanoclusters (NC) in gold is at a size 2-3 nm, where neither of these optical features is pronounced, is still poorly understood. All previous studies on this topic focused on metal-organic NC, capped with organic ligands and primarily discussed particle size effects. However, to which extent this phenomenon is also ruled by I) the number of valence electrons in the cluster, II) the energy of the contributing orbitals, or III) the polarizability of the electronic system is still scarcely understood. Thereto, size-controlled ligand-free, fully inorganic colloidal NC derived from laser fragmentation in liquids are ideal model materials. We will elucidate how electron-injecting and electron-withdrawing agents affect the transition regime discriminating A) weak charge transfer effects by ions B) strong but delocalized charge transfer from electron-rich supports like graphene, and C) strong, localized but ambivalent effects from covalently bound (Au-S) organic ligands. Additionally, element-specific features like bandgap energy and polarizability will be varied within a homologous coinage metal NC series of Au, Ag, and Cu, including AgAu and CuAu alloy NCs with of solid solution and segregated metal core ultrastructure. We will examine how doping of gold with another coinage metal with different orbital energy and polarizability affects the transition regime and how it is correlated with molar fraction and elemental mixing.