An easy-to-implement filter for separating photo-excited signals from topography in scanning tunneling microscopy

In order to achieve elemental and chemical sensitivity in scanning tunneling microscopy (STM), synchrotron x-rays have been applied to excite core-level electrons during tunneling. The x-ray photo-excitations result in tip currents that are superimposed onto conventional tunneling currents. While ca...

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Bibliographic Details
Published in:Review of scientific instruments 2013-06, Vol.84 (6), p.063704-063704
Main Authors: Wang, Kangkang, Rosenmann, Daniel, Holt, Martin, Winarski, Robert, Hla, Saw-Wai, Rose, Volker
Format: Article
Language:English
Subjects:
CURRENTS
ELECTRONS
EXCITATION
FILTERS
INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
LASERS
SCANNING TUNNELING MICROSCOPY
SENSITIVITY
SIGNALS
SYNCHROTRONS
TOPOGRAPHY
TUNNEL EFFECT
X RADIATION
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Summary:In order to achieve elemental and chemical sensitivity in scanning tunneling microscopy (STM), synchrotron x-rays have been applied to excite core-level electrons during tunneling. The x-ray photo-excitations result in tip currents that are superimposed onto conventional tunneling currents. While carrying important physical information, the varying x-ray induced currents can destabilize the feedback loop causing it to be unable to maintain a constant tunneling current, sometimes even causing the tip to retract fully or crash. In this paper, we report on an easy-to-implement filter circuit that can separate the x-ray induced currents from conventional tunneling currents, thereby allowing simultaneous measurements of topography and chemical contrasts. The filter and the schematic presented here can also be applied to other variants of light-assisted STM such as laser STM.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.4811652