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|Title:||ALS-CXRO Seminar | Alexander Gray|
|When:||07/18/2012 3:00 PM - 4:00 PM|
|Description:||ALS-CXRO Seminar Series|
Wed, July 18, 2012
Hard X-ray and Standing-Wave ExcitedPhotoemission: Emerging Techniques for Depth- Resolved Studies of Materials
In this talk I will describe several new directions in the field of x-ray photoelectron spectroscopy, made possible with the advent of third-generation synchrotron light sources and recent advances in the fields of x-ray optics and photoelectron detection. I will present several case-studies wherein hard x-ray photoelectron spectroscopy (HAXPES) in the multi-keV regime is used to probe the bulk properties of complex thin- film materials and heterojunctions, which would be otherwise impossible to investigate using conventional soft x-ray XPS . I will present the first results of hard x-ray angle- resolved photoemission measurements (HARPES), at excitation energies of 3 and 6 keV [2,3]. Compared to the traditional ARPES, carried out in the UPS regime (20-100 eV), this new technique enables one to probe on average 10-40 times deeper into the bulk. Finally, I will introduce a new photoemission technique (SWARPES) which combines soft x-ray ARPES with standing-wave (SW) excited photoelectron spectroscopy, wherein the intensity profile of the exciting x-ray radiation is tailored within the sample in order to provide a depth-selective probe of the electronic structure of buried layers and interfaces .
 A. X. Gray et al. Phys. Rev. B 84, 075104 (2011).
 A. X. Gray et al. Nature Materials 10, 759 (2011).
 A. X. Gray et al. Bulk Electronic Structure of the Dilute Near-Ferromagnetic Semiconductor Ga1- xMnxAs via Hard X-ray Angle-Resolved Photoemission. Nature Materials, under review.
 A. X. Gray et al. Depth-Resolved ARPES of Buried Layers and Interfaces via Soft X-ray Standing- Wave Excited Photoemission. In preparation.