Soft-X-ray ARPES at the Swiss Light Source: From 3D Materials to Buried Interfaces and Impurities

The fundamental advantage of soft-X-ray ARPES (SX-ARPES) with photon energies around 1 keV compared to the conventional vacuum-ultraviolet ARPES (VUV-ARPES) is an increase of the photoelectron escape depth. This enhances the bulk sensitivity of the ARPES experiment as well as enables access to burie...

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Bibliographic Details
Published in:Synchrotron radiation news 2014-03, Vol.27 (2), p.31-40
Main Authors: Strocov, Vladimir N., Kobayashi, Masaki, Wang, Xiaoqiang, Lev, Leonid L., Krempasky, Juraj, Rogalev, Victor V., Schmitt, Thorsten, Cancellieri, Claudia, Reinle-Schmitt, Mathilde L.
Format: Article
Language:English
Subjects:
Particle accelerators
Spectrum analysis
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Summary:The fundamental advantage of soft-X-ray ARPES (SX-ARPES) with photon energies around 1 keV compared to the conventional vacuum-ultraviolet ARPES (VUV-ARPES) is an increase of the photoelectron escape depth. This enhances the bulk sensitivity of the ARPES experiment as well as enables access to buried systems such as interfaces, heterostructures, and impurities. This advantage combines with resolution in three-dimensional (3D) momentum k, which, on the other hand, degrades upon further increase of energy into the hard-X-ray range. The main challenge of SX-ARPES is the valence band (VB) photoemission cross-section decreasing by a few orders of magnitude compared to the VUV-ARPES energy range. This problem can only be overpowered with advanced synchrotron radiation instrumentation delivering high photon flux. In this article, after a recap of the main virtues and current challenges of SX-ARPES, we report on the recent instrumental progress at the Swiss Light Source (SLS), where a new SX-ARPES facility was installed at the Advanced Resonant Spectroscopies (ADRESS) beamline. The high photon flux above 1013 photons/s/0.01%BW delivered by this beamline, combined with the optimized endstation geometry, has allowed us to break through the cross-section problem and, furthermore, push the applications of SX-ARPES from bulk materials to extremely photon-hungry cases of buried systems. Complementing the recent review of the whole field of soft- and hard-X-ray ARPES published in this magazine [1], we here focus on the recent SX-ARPES applications emerging with the advanced instrumentation of the SLS.
ISSN:0894-0886
1931-7344
DOI:10.1080/08940886.2014.889550