The bonding in thiolate protected gold nanoparticles from Au4f photoemission core level shifts

Density functional theory calculations are used to evaluate Au4f core level shifts of methyl thiolate protected Au-25, Au-102 and Au-144 nanoparticles. The shifts are found to provide sensitive fingerprints of the chemical environment. In particular, Au atoms in protective gold-thiolate complexes have higher binding energies than Au atoms with solely metal neighbors. The core level shifts for the nanoparticles are compared to the corresponding results for methyl thiolates adsorbed on Au(111) and implications for the understanding of the gold-sulfur bond is discussed