Abstract
Synchrotron X-ray Scanning Tunneling Microscopy (SX-STM) is a novel imaging technique capable of providing real space chemically specific mapping with a potential of reaching atomic resolution. Determination of chemical composition along with ultra-high resolution imaging by SX-STM can be realized through excitation of core electrons by incident X-rays when their energy is tuned to an absorption edge of a particular atom during raster scanning, as is done in the conventional STM experiments. In this work, we provide a brief summary and the current status of SX-STM and discuss its applications for material science. In particular, we discuss instrumentation challenges associated with the SX-STM technique and present early experiments on Cu doped ZrTe3 single crystals.
Highlights
Accurate determination of surface structure and chemical composition of materials at their interfaces and surfaces allows us to design and engineer material systems with specific physical properties and desired functionalities
Chemical sensitivity of Synchrotron X-ray Scanning Tunneling Microscopy (SX-Scanning tunneling microscopy (STM)) relies on excitation of core electrons in surface atoms by incident X-rays when their energy is tuned to an absorption edge of a specific element on the surfaces
The STM tip cannot distinguish between various electronic contributions, photoemission processes interfere with quantum tunneling and result in a background signal, making localized detection of chemically specific tunneling current extremely difficult
Summary
Accurate determination of surface structure and chemical composition of materials at their interfaces and surfaces allows us to design and engineer material systems with specific physical properties and desired functionalities. Scanning tunneling microscopy (STM) is a conventional tool used to atomically resolve surface morphology and conduct spectroscopic measurements on conductive surfaces [1,2]. Conventional STM only detects electrons in the valence or conduction bands but does not provide direct chemical composition of a conductive surface, which relies on excitation and detection of core-level electrons. Synchrotron X-ray Scanning Tunneling Microscopy (SX-STM) is complementary to those existing microscopic methods and enables ultra-high resolution elemental mapping. A SX-STM measurement is conducted when monochromatic X-ray beam illuminates the tip-sample gap area, while an SX-STM tip is raster scanned across the sample surface to acquire conventional STM data. Chemical sensitivity of SX-STM relies on excitation of core electrons in surface atoms by incident X-rays when their energy is tuned to an absorption edge of a specific element on the surfaces.
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