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Photoemission core level binding energies from multiple sized nanoparticles on the same support: TiO 2 (110)/Au

DOI: 10.1063/1.5135760 DOI Help

Authors: Andrew Mellor (University College London (UCL)) , Axel Wilson (Diamond Light Source) , Chi L. Pang (University College London (UCL)) , Chi M. Yim (University College London (UCL)) , Francesco Maccherozzi (Diamond Light Source) , Sarnjeet S. Dhesi (Diamond Light Source) , Christopher A. Muryn (The University of Manchester) , Hicham Idriss (University College London (UCL); SABIC – CRI, KAUST) , Geoff Thornton (University College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Chemical Physics , VOL 152

State: Published (Approved)
Published: January 2020
Diamond Proposal Number(s): 13723

Abstract: A novel method of measuring the core level binding energies of multiple sized nanoparticles on the same substrate is demonstrated using the early stage of Au nanoparticle growth on reduced r-TiO2(110). This method employed in situ scanning tunneling microscopy (STM) and microfocused X-ray photoemission spectroscopy. An STM tip-shadowing method was used to synthesize patterned areas of Au nanoparticles on the substrate with different coverages and sizes. Patterns were identified and imaged using a UV photoelectron emission microscope. The Au 4f core level binding energies of the nanoparticles were investigated as a function of Au nanoparticle coverage and size. A combination of initial and final state effects modifies the binding energies of the Au 4f core levels as the nanoparticle size changes. When single Au atoms and Au3 clusters are present, the Au 4f7/2 binding energy, 84.42 eV, is similar to that observed at a high coverage (1.8 monolayer equivalent), resulting from a cancellation of initial and final state effects. As the coverage is increased, there is a decrease in binding energy, which then increases at a higher coverage to 84.39 eV. These results are consistent with a Volmer-Weber nucleation-growth model of Au nanoparticles at oxygen vacancies, resulting in electron transfer to the nanoparticles.

Journal Keywords: Electron microscopy; Photoelectric effect; Electron diffraction; Crystallographic defects; Photoelectron emission; Scanning tunneling microscopy; Catalysis; Charge transfer; X-ray photoelectron spectroscopy; Nanoparticles

Subject Areas: Physics, Materials

Instruments: I06-Nanoscience