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CEMS scientists publish pioneering research on atomic core-level orbitals

May 2, 2016 - A collaborative team of CEMS scientists recently published their research, “Probing core-electron orbitals by scanning transmission electron microscopy and measuring the delocalization of core-level excitations” in Physical Review B, the largest and most comprehensive international journal specializing in condensed matter and materials physics. The team, consisting of materials science and engineering graduate student Andrew Xu, CEMS alumnus Michael Oldyzko (PhD MSE ’15) and Professors Jong Seok Jeong, Bharat Jalan, and Andre Mkhoyan, introduced a simple, but inventive use of a recently installed FEI aberration-corrected scanning transmission electron microscope at the University of Minnesota to image atomic core-level electron orbitals. These core-level orbitals, approximately 0.2 – 0.5 Angstrom in size, are even smaller than the bonding orbitals previously imaged by other methods. These core-level orbitals are the smallest objects ever imaged.

To demonstrate the method, they imaged not one but four different core-level orbitals in a STO crystal: two from Sr atoms, orbitals 1s and 2p, and two from Ti atoms, also 1s and 2p. Professor Andre Mkhoyan, one of the researchers on the project, remarked, “I believe that this first-ever imaging of core-level orbitals amounts to achieving a grand challenge of modern microscopy, going beyond seeing atoms to seeing sub-atomic features. It is the culmination of decades of scientific and engineering refinement by this research community!”

The image shows experimentally observed projected excitation potentials for 1s and 2p orbitals of Sr and Ti, including the effects of atomic thermal vibrations and excitation broadening, retrieved from EDX maps.

Related Link: http://journals.aps.org/prb/abstract/10.1103/PhysRevB.93.165140

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