Topic
Photoemission spectroscopy
About: Photoemission spectroscopy is a research topic. Over the lifetime, 10821 publications have been published within this topic receiving 250888 citations. The topic is also known as: photoelectron spectroscopy & PES.
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TL;DR: In this article, the phase structure and microstructure of nanophase zinc oxide samples were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM).
Abstract: Nanophase zinc oxide samples were synthesized by a two-step solid-state reaction method. The phase structure and microstructure were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The vibrational Raman spectra were compared with those from the bulk and their grain size dependence was also examined. Their photoelectric behavior was studied by X-ray photoelectron spectroscopy (XPS). The peaks at 1044.5 and 1021.4 eV were recorded as corresponding to the respective binding energies of Zn 2p1/2 and Zn 2p3/2, and the photoelectron spectrum of O 1s in the as-prepared powder was located at 531.2 eV. A strong visible emission centered at 580 nm was clearly observed in the nanosized zinc oxide at room temperature. Photoluminescence (PL) spectra were investigated as a function of grain size after different heat treatments. The origin of the luminescence is attributed to the recombination of electrons in singly occupied oxygen vacancies with photoexcited holes in the valence band.
151 citations
TL;DR: In this article, the authors provide sufficient experimental evidence to support the reliability and the consistency of the angle-resolved photoemission spectroscopy measurements over a wide range of material compositions.
Abstract: Angle-resolved photoemission spectroscopy allows direct visualization and experimental determination of the electronic structure of crystals in the momentum space, including the precise characterization of the Fermi surface and the superconducting order parameter. It is thus particularly suited for investigating multi-band systems such as the Fe-based superconductors. In this review, we cover several aspects of these recently discovered materials that have been addressed by this technique, with a special emphasis on their superconducting gap and their Fermi surface topology. We provide sufficient experimental evidence to support the reliability and the consistency of the angle-resolved photoemission spectroscopy measurements over a wide range of material compositions.
150 citations
TL;DR: In this paper, the authors investigated the variation of the work function properties of MoS2 films prepared with chemical vapor deposition (CVD) on SiO2 substrates with the number of film layers.
Abstract: The electrical properties of two-dimensional atomic sheets exhibit remarkable dependences on layer thickness and surface chemistry. Here, we investigated the variation of the work function properties of MoS2 films prepared with chemical vapor deposition (CVD) on SiO2 substrates with the number of film layers. Wafer-scale CVD MoS2 films with 2, 4, and 12 layers were fabricated on SiO2, and their properties were evaluated by using Raman and photoluminescence spectroscopies. In accordance with our X-ray photoelectron spectroscopy results, our Kelvin probe force microscopy investigation found that the surface potential of the MoS2 films increases by ∼0.15 eV when the number of layers is increased from 2 to 12. Photoemission spectroscopy (PES) with in-situ annealing under ultra high vacuum conditions was used to directly demonstrate that this work function shift is associated with the screening effects of oxygen or water molecules adsorbed on the film surface. After annealing, it was found with PES that the su...
150 citations
TL;DR: In this article, the effect of an interface dipole layer on the energy level alignment at organic-conductor interfaces is studied on a copper phthalocyanine (CuPc) monolayer/electric dipole layers/graphite system via ultraviolet photoemission spectroscopy (UPS) and metastable atom electron spectroscopic.
Abstract: The effect of an interface dipole layer on the energy level alignment at organic-conductor interfaces is studied on a copper phthalocyanine (CuPc) monolayer/electric dipole layer/graphite system via ultraviolet photoemission spectroscopy (UPS) and metastable atom electron spectroscopy. An oriented monolayer of the OTi-phthalocyanine molecule, which has an electric dipole moment, is grown on graphite to yield a well-defined dipole layer with the vacuum side negatively charged. The CuPc monolayer is sequentially deposited on the dipole layer kept at $123\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. This weakly interacting system made of a very thin organic layer on top of a very thin dipole layer is in thermodynamic equilibrium. The UPS data from the system grown with and without the interface dipole layer show that the binding energy of the highest occupied state of the CuPc monolayer decreases when the dipole layer is inserted. The binding energy shift is in excellent agreement with the increase in vacuum level energy of the graphite substrate upon deposition of the dipole layer. The results show that the Fermi level of the CuPc shifts toward the valence states when the interface dipole layer is inserted.
150 citations
TL;DR: In this article, X-ray photoelectron spectroscopy (XPS) was used to quantify the defect concentration and to examine the defect electronic structure, based on their calculation of defect concentrations and the comparison of their results with results and models from the literature, they conclude that oxygen vacancies induced by electron beams in the current study are mostly from the bridging oxygen sites, in agreement with the previous work.
150 citations