Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 71: Scanning Probe Techniques and New Experimental Methods
O 71.15: Poster
Mittwoch, 9. März 2016, 18:15–20:30, Poster A
Identification of nanoscale phases using Low Energy Electron Microscopy. — •Martin Hoppe, Jan Höcker, Jens Falta, and Jan Ingo Flege — Universität Bremen, Germany
Low Energy Electron Microscopy (LEEM) is an established method to investigate surface structures and morphologies with a lateral resolution in the few nanometer range. The main benefits are the in situ capabilities of the instrument enabling surface monitoring during manipulation such as growth and chemical reactions. In LEEM, crystal phases differing in structure or chemical composition may exhibit different intensities at a given energy. But, this does not allow for a definite identification especially on very heterogeneous surfaces. The latter can be achieved using intensity-voltage (I(V)) curves
as a reliable fingerprint for each phase.1 We show that the correlation coefficient or R2-factor2 can be used to compare unknown LEEM-I(V) curves to reference spectra and thus to distinguish phases on the 10 nm scale. Performing a pixel-wise automated comparison, 2D maps of the surface phases can be generated and, in a dynamic I(V)-LEEM experiment, their development during sample manipulation can be monitored. This new method will be demonstrated using examples from ruthenium oxidation3 and chemical reactions at cerium oxide surfaces4.
[1] J. I. Flege et al., Phys. Status Solidi RRL 6, 463 (2014)
[2] M.A. Van Hove, W. H. Weinberg, and C.-M. Chan, Low-Energy Electron Diffraction, Springer (1986)
[3] J. I. Flege et al., ACS Nano 9, 8468-8473 (2015)
[4] J. Höcker et al., Adv. Mater. Interfaces, in press (2015)