| 1. |
- Chuang, Yi-De, et al.
(författare)
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Modular soft x-ray spectrometer for applications in energy sciences and quantum materials
- 2017
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 88:1
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Tidskriftsartikel (refereegranskat)abstract
- Over the past decade, the advances in grating-based soft X-ray spectrometers have revolutionizedthe soft X-ray spectroscopies in materials research. However, these novel spectrometers are mostlydedicated designs, which cannot be easily adopted for applications with diverging demands. Here wepresent a versatile spectrometer design concept based on the Hettrick-Underwood optical scheme thatuses modular mechanical components. The spectrometer’s optics chamber can be used with gratingsoperated in either inside or outside orders, and the detector assembly can be reconfigured accordingly.The spectrometer can be designed to have high spectral resolution, exceeding 10 000 resolvingpower when using small source (∼1 µm) and detector pixels (∼5 µm) with high line density gratings(∼3000 lines/mm), or high throughput at moderate resolution. We report two such spectrometers withslightly different design goals and optical parameters in this paper. We show that the spectrometer withhigh throughput and large energy window is particularly useful for studying the sustainable energymaterials. We demonstrate that the extensive resonant inelastic X-ray scattering (RIXS) map of batterycathode material LiNi1/3Co1/3Mn1/3O2 can be produced in few hours using such a spectrometer.Unlike analyzing only a handful of RIXS spectra taken at selected excitation photon energies across theelemental absorption edges to determine various spectral features like the localized dd excitations andnon-resonant fluorescence emissions, these features can be easily identified in the RIXS maps. Studyingsuch RIXS maps could reveal novel transition metal redox in battery compounds that are sometimeshard to be unambiguously identified in X-ray absorption and emission spectra. We propose that thismodular spectrometer design can serve as the platform for further customization to meet specificscientific demands.
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| 2. |
- He, Qinggang, et al.
(författare)
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Electrochemical and spectroscopic characterization of a dicobalt macrocyclic Pacman complex in the catalysis of the oxygen reduction reaction in acid media
- 2013
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Ingår i: Journal of Porphyrins and Phthalocyanines. - : World Scientific Pub Co Pte Ltd. - 1088-4246 .- 1099-1409. ; 17:4, s. 252-258
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Tidskriftsartikel (refereegranskat)abstract
- The dicobalt complex [Co-2(L-2)] of a Schiff-base pyrrole macrocycle adopts a Pacman structure in solution and the solid state and shows much greater catalytic activity and selectivity for the four-electron oxygen reduction reaction (ORR) than the mononuclear cobalt phthalocyanine (CoPc) counterpart. Soft X-ray absorption spectroscopy (XAS) shows that the Co center in Co-2(L-2) is of the same valence as mononuclear CoPc. However, the former complex shows higher unoccupied Co 3d density which is believed to be beneficial for electron transfers. Furthermore, the XAS data suggests that the crystal fields for Co-2(L-2) and CoPc are different, and that an interaction remains between two Co atoms in Co-2(L-2). DFT calculations imply that the sterically hindered, cofacial structure of the dicobalt complex is critical for the operation of the four-electron reaction pathway during the ORR.
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| 3. |
- Lee, Jenn-Min, et al.
(författare)
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The magnetic order in multiferroic DyMnO3
- 2021
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 246
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Tidskriftsartikel (refereegranskat)abstract
- With flexibility in tuning their electric and magnetic properties, multiferroics can be used in information exchange and storage in ways that are very different from the present electronic materials. Here we use resonant soft x-ray scattering spectroscopy to study the -type and -type (0, 1-, 0) diffraction peaks from sinusoidal antiferromagnetic spin order in multiferroic DyMnO. By comparing the temperature dependence of ordering wave vectors , peak intensities , and correlation lengths measured at Mn -, O -, and Dy -edges, we show that the nearly perfect locking between the ordering wave vectors from Dy states and Mn 3 orbitals manifesting the second harmonic diffraction peak implies the notable orbital involvement in the coupling between Mn and Dy spins. Our DFT calculations further suggest that the lattice response to different antiferromagnetic ground states (A-type versus E-type) is much weaker in TbMnO, in agreement with previous claim that the symmetric exchange interaction can be an important factor for understanding the ferroelectricity in DyMnO than in TbMnO.
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