Regular Article

The effects of Pt doping on the optical properties of Au₂₀

¹ Physics Department, King’s College, London WC2R 2LS, UK
² Nano-Bio Spectroscopy Group and European Theoretical Spectroscopy Facility, Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnologia, Universidad del Pais Vasco, 20018 San Sebastian, Spain
³ Ikerbasque, Basque Foundation for Science, Plaza de Euskadi 5, 48009 Bilbao, Spain
⁴ Physics Department, Universita di Milano “La Statale”, 20133, Italy

e-mail: robert.m.jones@kcl.ac.uk
e-mail: roberto.dagosta@ehu.es
e-mail: francesca.baletto@unimi.it

Received: 17 January 2022
Received in final form: 3 March 2022
Accepted: 17 March 2022
Published online: 12 August 2022

Abstract

We consider the doping of Pt onto small Au₂₀ clusters, identifying the effects that this alloying has upon the optical and static properties of each candidate nanoalloy. By performing real-time time dependent density functional theory calculations, we determine that the electronic structure and, by extension, the optical absorption spectrum strongly depend on the position of a Pt dopant; either as substitutional defect, or as an adsorbed atom on the Au-surface. Indeed, we find that by varying the local positions, we are able to strongly influence the electronic and optical properties of complex nanoalloys. Of particular interest is the profound impact on the HOMO–LUMO gap of Au₂₀ – shrinking or growing depending on the location of a Pt doping. By considering different possible locations and morphologies for the introduced Pt, we identify alloying types which may have a greater probability of supporting collective plasma oscillations.