Sementa Luca, Stener Mauro, Fortunelli Alessandro
CNR-IPCF, Consiglio Nazionale delle Ricerche, 56124 Pisa, Italy.
Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, 34127 Trieste, Italy.
Molecules. 2021 Nov 18;26(22):6961. doi: 10.3390/molecules26226961.
We report a computational study and analysis of the optical absorption processes of Ag and Au clusters deposited on the magnesium oxide (100) facet, both regular and including point defects. Ag and Au are taken as models of metal nanoparticles and their plasmonic response, MgO as a model of a simple oxide support. We consider oxide defects both on the oxygen anion framework (i.e., a neutral oxygen vacancy) and in the magnesium cation framework (i.e., replacing Mg with a transition metal: Cu or Co). We relax the clusters' geometries via Density-Functional Theory (DFT) and calculate the photo-absorption spectra via Time-Dependent DFT (TDDFT) simulations on the relaxed geometries. We find that the substrate/cluster interaction induces a broadening and a red-shift of the excited states of the clusters, phenomena that are enhanced by the presence of an oxygen vacancy and its localized excitations. The presence of a transition-metal dopant does not qualitatively affect the spectral profile. However, when it lies next to an oxygen vacancy for Ag, it can strongly enhance the component of the cluster excitations perpendicular to the surface, thus favoring charge injection.
我们报告了一项关于沉积在氧化镁（100）晶面上的银和金团簇（包括规则的和含有点缺陷的）光吸收过程的计算研究与分析。银和金被用作金属纳米颗粒及其等离子体响应的模型，氧化镁作为简单氧化物载体的模型。我们考虑了氧阴离子框架上的氧化物缺陷（即中性氧空位）以及镁阳离子框架中的缺陷（即用过渡金属铜或钴替代镁）。我们通过密度泛函理论（DFT）优化团簇的几何结构，并在优化后的几何结构上通过含时密度泛函理论（TDDFT）模拟计算光吸收光谱。我们发现，衬底/团簇相互作用会导致团簇激发态的展宽和红移，氧空位及其局部激发的存在会增强这些现象。过渡金属掺杂剂的存在不会在定性上影响光谱轮廓。然而，当银旁边存在氧空位时，它可以强烈增强团簇垂直于表面的激发分量，从而有利于电荷注入。
