Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 4: New Methods: Experiments
O 4.5: Vortrag
Montag, 18. März 2024, 11:30–11:45, MA 005
Quantifying monolayer coverage of endofullerenes by x-ray absorption spectroscopy from equivalent implanted ion doses — •W.C Lee1, L. Yu1, J. Oscarsson2, M. W. Ochapski3, R. Sagehashi1, Y. Zhang4, A. A. Popov4, Z. M. Gebeyehu3, L. Martini3, S. Forti3, C. Coletti3, B. Delley5, M. Muntwiler5, D. Primetzhofer2, and T. Greber1 — 1Physik-Institut, Universität Zürich, Switzerland — 2Tandem Laboratory, Uppsala University, Sweden — 3Istituto Italiano di Technologia, Pisa, Italy — 4Leibniz-Institute, Dresden, Germany — 5Paul Scherrer Institute, Switzerland
With x-ray absorption spectroscopy (XAS), the structure of magnetic atoms in molecules may be accessed directly [1]. For Ho3N@C80 endofullerenes on graphene/SiO2, we calibrated the surface coverage by comparing the molecular XAS signal with implanted Ho ion doses of 3×1014 cm−2 that are directed to SiO2 with energies between 2 and 115 keV. The corresponding Ho M45 intensity as a function of implantation depth d can be extrapolated to the zero-depth intensity of absorbed molecules. The Ho signal attenuation scales with exp(-d/Λ), with Λ=10.3±0.7 nm. The Si K-edge signal attenuation reveals an influence of the implantation process on the Si density. The XA spectra indicate trivalent Ho for both molecules and implants, while spectral differences and comparison to multiplet theory [2] suggest an isotropic J=8 Ho 4f electron distribution for implants and Jz=±8 ground states in the molecules due to the defined intramolecular ligand field.
[1] R. Westerström, et al., Phys. Rev. Lett., 087201 (2015)[2] A. Uldry, et al., Phys. Rev. B, 85, 125133 (2012)
Keywords: Endofullerenes; Coverage calibration; x-ray absorption spectroscopy; final state multiplet calculations; ion implantation