Optical Absorption of Small Palladium‐Doped Gold Clusters. (21st April 2016)

• Record Type: Journal Article
• Authors: Kaydashev, Vladimir; Ferrari, Piero; Heard, Christopher; Janssens, Ewald; Johnston, Roy L.; Lievens, Peter
• Is Part Of: Particle and particle systems characterization. Volume 33:Number 7(2016:Jul.)
• Page Start: 364
• Page End: 372
• Publication Date: 2016-04-21
• Subjects: gold clusters -- optical absorption -- palladium doping; Particles -- Periodicals; 620.43
• DOI: 10.1002/ppsc.201600036
• Languages: English
• ISSNs: 0934-0866

Abstract

Abstract : The effect of Pd doping on the structure and optical absorption of small cationic gold clusters is investigated by a combined photodissociation spectroscopy and time‐dependent density functional theory study of Au n + Ar p and PdAu n ‐1 + Ar p ( n = 4, 5; p = 0, 1). While pure Au clusters are planar, the Pd‐doped clusters are 3D. UV–visible absorption is studied in the 2.0–4.7 eV photon energy range, allowing the observation of previously unreported absorption bands for Au4 + and Au4 + Ar. The oscillator strength of the optical transitions is dramatically reduced upon incorporating a Pd atom in Au4 + and Au4 + Ar, while this effect is less pronounced for Au5 + Ar. Analysis of the electron density transfer shows a different influence of Pd with size. While Pd has a formal negative charge in Au3 Pd +, in Au4 Pd + most of the charge is attracted by the highly coordinated central Au atom, leaving Pd positively charged, also affecting the induced structural changes. In addition, orbital analysis of the optical transitions is carried out in order to identify the levels involved in the optical absorption of the pure Au and Pd doped clusters. A reduction of the s density near the Fermi energy, induced by Pd doping, causes a quenching of optical absorption. Abstract : The effect of a single Pd dopant atom in the optical absorption of the small gas‐phase Au4 + and Au5 + clusters is studied by a combination of photodissociation spectroscopy and density functional theory calculations. A quenching of most absorption bands is observed and attributed to charge transfer and structural changes induced by the Pd dopant atom.