scholarly journals Direct observation of minibands in a twisted graphene/WS2 bilayer

2020 ◽  
Vol 6 (14) ◽  
pp. eaay6104 ◽  
Author(s):  
Søren Ulstrup ◽  
Roland J. Koch ◽  
Simranjeet Singh ◽  
Kathleen M. McCreary ◽  
Berend T. Jonker ◽  
...  
Keyword(s):  
Optical Measurements ◽  
Photoemission Spectroscopy ◽  
Transition Metal Dichalcogenide ◽  
Electron Hole ◽  
Final State ◽  
X Ray ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Electron Hole Pair ◽  
Twisted Graphene ◽  
Quasiparticle Band

Stacking two-dimensional (2D) van der Waals materials with different interlayer atomic registry in a heterobilayer causes the formation of a long-range periodic superlattice that may bestow the heterostructure with properties such as new quantum fractal states or superconductivity. Recent optical measurements of transition metal dichalcogenide (TMD) heterobilayers have revealed the presence of hybridized interlayer electron-hole pair excitations at energies defined by the superlattice potential. The corresponding quasiparticle band structures, so-called minibands, have remained elusive, and no such features have been reported for heterobilayers composed of a TMD and another type of 2D material. We introduce a new x-ray capillary technology for performing microfocused angle-resolved photoemission spectroscopy with a spatial resolution of ~1 μm, and directly observe minibands at certain twist angles in mini Brillouin zones (mBZs). We discuss their origin in terms of initial and final state effects by analyzing their dispersion in distinct mBZs.

Few-Layered MoS2 Nanostructures for Highly Efficient Visible Light Photocatalysis

NANO ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. 1650114 ◽  
Author(s):  
Dan Li ◽  
Jianwei Li ◽  
Caiqin Han ◽  
Xinsheng Zhao ◽  
Haipeng Chu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Electrochemical Impedance ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
Electrochemical Impedance Spectra ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Hole Pair

Few-layered MoS2 nanostructures were successfully synthesized by a simple hydrothermal method without the addition of any catalysts or surfactants. Their morphology, structure and photocatalytic activity were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, electrochemical impedance spectra and UV-Vis absorption spectroscopy, respectively. These results show that the MoS2 nanostructures synthesized at 180[Formula: see text]C exhibit an optimal visible light photocatalytic activity (99%) in the degradation of Rhodamine B owing to the relatively easier adsorption of pollutants, higher visible light absorption and lower electron–hole pair recombination.

Aging of the surface of an Al-Cr-Fe approximant phase in ambient conditions: chemical composition and physical properties

2003 ◽  
Vol 805 ◽  
Author(s):  
D. Veys ◽  
P. Weisbecker ◽  
V. Fournée ◽  
B. Domenichini ◽  
S. Weber ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Mass Spectroscopy ◽  
Electrochemical Behavior ◽  
Stable State ◽  
Photoemission Spectroscopy ◽  
Atmospheric Conditions ◽  
Electrical Model ◽  
Ambient Conditions ◽  
X Ray ◽  
Angle Resolved Photoemission Spectroscopy

ABSTRACTWe have investigated the surface properties of quasicrystalline and approximant phases in the Al-(Cu)-Cr-Fe system upon aging in ambient conditions. We found that some of these properties (like the electrochemical behavior, wetting or friction) slowly evolves with the length of exposure to normal atmospheric conditions, reaching a stable state only after several days. This report essentially focuses on one of these alloys, an Al65Cr27Fe8 approximant phase with g-brass structure. In a first part, we describe the effect of aging on the electrochemical behavior of this alloy and we propose an interpretation based on a simple electrical model of the oxidized surface. In a second part, we present a model describing the surface as a stacking of several layers (oxides, oxy-hydroxides, contamination) whose thickness evolves with time. The model is supported by X-ray reflectivity, angle-resolved photoemission spectroscopy and secondary neutral mass spectroscopy measurements.

scholarly journals Itinerant U5fband states in the layered compoundUFeGa5observed by soft x-ray angle-resolved photoemission spectroscopy

2006 ◽  
Vol 73 (12) ◽  
Author(s):  
Shin-ichi Fujimori ◽  
Kota Terai ◽  
Yukiharu Takeda ◽  
Tetsuo Okane ◽  
Yuji Saitoh ◽  
...  
Keyword(s):  
Photoemission Spectroscopy ◽  
X Ray ◽  
Angle Resolved Photoemission Spectroscopy

Electronic Structure of Trivalent Compound EuPd3 Studied by Soft X-ray Angle-resolved Photoemission Spectroscopy

2020 ◽  
Vol 89 (4) ◽  
pp. 044704 ◽  
Author(s):  
Ikuto Kawasaki ◽  
Masaaki Kobata ◽  
Shin-ichi Fujimori ◽  
Yukiharu Takeda ◽  
Hiroshi Yamagami ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Photoemission Spectroscopy ◽  
X Ray ◽  
Angle Resolved Photoemission Spectroscopy

scholarly journals Evidence of Electron-Hole Imbalance in WTe 2 from High-Resolution Angle-Resolved Photoemission Spectroscopy

2017 ◽  
Vol 34 (9) ◽  
pp. 097305 ◽  
Author(s):  
Chen-Lu Wang ◽  
Yan Zhang ◽  
Jian-Wei Huang ◽  
Guo-Dong Liu ◽  
Ai-Ji Liang ◽  
...  
Keyword(s):  
High Resolution ◽  
Photoemission Spectroscopy ◽  
Electron Hole ◽  
Angle Resolved Photoemission Spectroscopy

Radiation Hard Devices Based on SiC

2006 ◽  
Vol 527-529 ◽  
pp. 1473-1476 ◽  
Author(s):  
Evgenia V. Kalinina ◽  
Anatoly M. Strel'chuk ◽  
Alexander A. Lebedev ◽  
Nikita B. Strokan ◽  
Alexander M. Ivanov ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Signal Amplitude ◽  
High Energy ◽  
Pair Creation ◽  
Transistor Structure ◽  
Electron Hole ◽  
X Ray ◽  
Electron Hole Pair ◽  
Radiation Hard ◽  
High Energy Particles

The effect of irradiation with protons, electrons, neutrons, x-ray radiation and gamma-ray photons as well as with different ions on properties of starting SiC material and devices based on it was studied. The rectifying properties of the diode structures, which degraded as a result of irradiation with high energy particles, were recovered at higher operation temperatures. The transistor structure SiC-based detectors were realized with the signal amplification by a factor of tens under irradiation. The energy resolution of 0.34 %, commensurable with Si-detectors, has been achieved for SiC detectors and is correct for all classes of short range ions. The maximum signal amplitude corresponds, in SiC, to a mean electron-hole pair creation energy of 7.7 eV.

scholarly journals Development of a soft X-ray angle-resolved photoemission system applicable to 100 µm crystals

2011 ◽  
Vol 18 (6) ◽  
pp. 879-884 ◽  
Author(s):  
Takayuki Muro ◽  
Yukako Kato ◽  
Tomohiro Matsushita ◽  
Toyohiko Kinoshita ◽  
Yoshio Watanabe ◽  
...  
Keyword(s):  
Electronic States ◽  
Spot Size ◽  
Optical Microscope ◽  
Photoemission Spectroscopy ◽  
Beam Spot ◽  
X Ray ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Clear Band ◽  
Sample Position

A system for angle-resolved photoemission spectroscopy (ARPES) of small single crystals with sizes down to 100 µm has been developed. Soft X-ray synchrotron radiation with a spot size of ∼40 µm × 65 µm at the sample position is used for the excitation. Using this system an ARPES measurement has been performed on a Si crystal of size 120 µm × 100 µm × 80 µm. The crystal was properly oriented on a sample stage by measuring the Laue spots. The crystal was cleavedin situwith a microcleaver at 100 K. The cleaved surface was adjusted to the beam spot using an optical microscope. Consequently, clear band dispersions along the Γ–Xdirection reflecting the bulk electronic states were observed with a photon energy of 879 eV.

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