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Optical Absorption of Small Palladium‐Doped Gold Clusters
Author(s) -
Kaydashev Vladimir,
Ferrari Piero,
Heard Christopher,
Janssens Ewald,
Johnston Roy L.,
Lievens Peter
Publication year - 2016
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.201600036
Subject(s) - absorption (acoustics) , density functional theory , oscillator strength , absorption spectroscopy , doping , palladium , chemistry , atom (system on chip) , quenching (fluorescence) , atomic physics , materials science , photochemistry , fluorescence , spectral line , computational chemistry , optics , biochemistry , physics , optoelectronics , catalysis , astronomy , computer science , composite material , embedded system
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 Au 4 + and Au 4 + Ar. The oscillator strength of the optical transitions is dramatically reduced upon incorporating a Pd atom in Au 4 + and Au 4 + Ar, while this effect is less pronounced for Au 5 + Ar. Analysis of the electron density transfer shows a different influence of Pd with size. While Pd has a formal negative charge in Au 3 Pd + , in Au 4 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.