Publications by authors named "Kejin J Zhou"

2 Publications

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Transition-Metal Nanoparticle Oxidation in a Chemically Nonhomogenous Environment Revealed by 2p3d Resonant X-ray Emission.

J Phys Chem Lett 2013 Apr 25;4(7):1161-6. Epub 2013 Mar 25.

‡Paul Scherrer Institut (PSI), Swiss Light Source, CH-5232 Villigen, Switzerland.

X-ray absorption spectroscopy (XAS) is often employed in fields such as catalysis to determine whether transition-metal nanoparticles are oxidized. Here we show 2p3/2 XAS and 2p3d resonant X-ray emission spectroscopy (RXES) data of oleate-coated cobalt nanoparticles with average diameters of 4.0, 4.2, 5.0, 8.4, and 15.2 nm. Two particle batches were exposed to air for different periods of time, whereas the others were measured as synthesized. In the colloidal nanoparticles, the cobalt sites can have different chemical environments (metallic/oxidized/surface-coordinated), and it is shown that most XAS data cannot distinguish whether the nanoparticles are oxidized or surface-coated. In contrast, the high-energy resolution RXES spectra reveal whether more than the first metal layer is oxidized based on the unique energetic separation of spectral features related to the formal metal (X-ray fluorescence) or to a metal oxide (d-d excitations). This is the first demonstration of metal 2p3d RXES as a novel surface science tool.
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http://dx.doi.org/10.1021/jz4002696DOI Listing
April 2013

A multispectroscopic study of 3d orbitals in cobalt carboxylates: the high sensitivity of 2p3d resonant X-ray emission spectroscopy to the ligand field.

Angew Chem Int Ed Engl 2013 Jan 6;52(4):1170-4. Epub 2012 Dec 6.

Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.

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http://dx.doi.org/10.1002/anie.201204855DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3564409PMC
January 2013
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