Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 53: Scanning Probe Methods II
O 53.2: Vortrag
Mittwoch, 13. März 2013, 16:15–16:30, H31
Improvement of STM Resolution with H-sensitized Tips — Jose Ignacio Martínez1, •Enrique Abad1,2, César González1, Fernando Flores1, and José Ortega1 — 1Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain — 2Computational Biochemistry Group, Institut für Theoretische Chemie, Universität Stuttgart, Stuttgart, Germany
The improvement of spatial resolution in STM is attaining a lot of attention in diverse fields such as Surface Science [1]. In particular, recent Scanning Tunneling Hydrogen Microscopy (STHM) experiments on PTCDA/Au(111) have shown unprecedented intramolecular and intermolecular spatial resolution [1]. In our work, we analyze the effect on the STM images of hydrogen interacting with tip or sample, using an accurate STHM theoretical simulation technique [2]. Notice that the standard Tersoff-Hamman approach cannot take into account the influence of the hydrogen in the STM image.
We find that the STHM resolution enhancement is due to atomic H adsorbed on the tip [3]. The adsorbed H-atoms induce important changes in the Density of States (DOS) at the Fermi level (EF) of the tip, increasing its total value, and making it more directional. Also, due to the interaction with the tip, EF is shifted to the middle of the PTCDA LUMO peak, increasing the DOS of the sample at EF [3].
[1] L. Gross, Nat. Chem. 3, 273 (2011).
[2] J. I. Martínez, E. Abad, et al. Org. Electron. 13, 399 (2012).
[3] J. I. Martínez, E. Abad, et al., Phys. Rev. Lett. 108, 246102 (2012).