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.
Papers published on a yearly basis
Papers
More filters
TL;DR: The direct observation of valley-dependent out-of-plane spin polarization in an archetypal transition-metal dichalcogenide--MoS2--using spin- and angle-resolved photoemission spectroscopy is reported, in fair agreement with a first-principles theoretical prediction.
Abstract: The valley degree of freedom of electrons is attracting growing interest as a carrier of information in various materials, including graphene, diamond and monolayer transition-metal dichalcogenides. The monolayer transition-metal dichalcogenides are semiconducting and are unique due to the coupling between the spin and valley degrees of freedom originating from the relativistic spin-orbit interaction. Here, we report the direct observation of valley-dependent out-of-plane spin polarization in an archetypal transition-metal dichalcogenide--MoS2--using spin- and angle-resolved photoemission spectroscopy. The result is in fair agreement with a first-principles theoretical prediction. This was made possible by choosing a 3R polytype crystal, which has a non-centrosymmetric structure, rather than the conventional centrosymmetric 2H form. We also confirm robust valley polarization in the 3R form by means of circularly polarized photoluminescence spectroscopy. Non-centrosymmetric transition-metal dichalcogenide crystals may provide a firm basis for the development of magnetic and electric manipulation of spin/valley degrees of freedom.
387 citations
01 Mar 1992-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: The atomic and electronic structure of polymer films undergoes deep modifications during high energy (keV-MeV) ion irradiation, from molecular solid to amorphous material as discussed by the authors, and the concentration of trigonal carbon (sp 2 ) in the polymer changes with ion fluence (10 11 −10 14 ions cm 2 ) and stabilizes to a value of 20% independently on the initial chemical structure of the irradiated sample.
Abstract: The atomic and electronic structure of polymer films undergoes deep modifications during high energy (keV-MeV) ion irradiation, from molecular solid to amorphous material. At low energy density (10 22 –10 24 eV cm 3 ) typical effects include chain scissions, crosslinks, molecular emission and double bonds formation. In hydrocarbon polymer (polystyrene, polyethylene) the main effect of irradiation is the formation of new bonds as detected by molecular weight distribution, solubility and optical measurements. Moreover the concentration of trigonal carbon (sp 2 ) in the polymer changes with ion fluence (10 11 –10 14 ions cm 2 ) and stabilizes to a value of 20% independently on the initial chemical structure of the irradiated sample. Photoemission spectroscopy shows an evolution of valence band states from localized to extended states. At high energy density (10 24 –10 26 eV cm 3 ) the irradiated polymer continues to evolve showing spectroscopic characteristics close to those of hydrogenated amorphous carbon. Trigonal carbon concentration changes with ion fluence (10 14 –10 16 ions cm 2 ) reaching the steady state value of 60% and the hydrogen concentration decreases to 20%. Moreover the values of the optical gap (2.5–0.5 eV) suggest the presence of medium range order in the obtained hydrogenated amorphous carbon. These values are consistent with the formation of graphitic clusters, whose size goes from 5 A to 20 A by changing the ion fluence (or energy density).
387 citations
TL;DR: In this article, the electron-phonon interaction operates on a longer timescale of several psec, the electrons are decoupled from lattice and it is possible to heat the electrons alone up to several thousand K.
Abstract: Electron heating in metals by ultrashort laser pulses has been under intensive investigations in recent years. It is generally believed that in a very short time (< 1-2 fsec) after the optical excitation, the electrons equilibrate among themselves via the electron-electron interaction, and establish a thermal Fermi-Dirac distribution at an elevated temperature. The electron-phonon interaction operates on a longer timescale of several psec, the electrons are decoupled from lattice and it is possible to heat the electrons alone up to several thousand K. However no direct measurements of the electron energy distribution function in laser-heated metals have been reported so far. We have used ultraviolet photoemission spectroscopy to directly obtain the energy distribution function with 500 fsec time resolution.
385 citations
TL;DR: In this paper, the synthesis and detailed characterization of graphite thin films produced by thermal decomposition of the face of a 6H-SiC wafer, demonstrating the successful growth of single crystalline films down to approximately one graphene layer, was carried out in ultrahigh vacuum (UHV) conditions.
384 citations
TL;DR: In this paper, the photoemission line shapes of the optimally doped cuprate Bi(2)Sr(2),CaCu(2)/O(8+delta) were studied in the direction of a node in the superconducting order parameter by means of very high resolution photo-emission spectroscopy.
Abstract: The photoemission line shapes of the optimally doped cuprate Bi(2)Sr(2)CaCu(2)O(8+delta) were studied in the direction of a node in the superconducting order parameter by means of very high resolution photoemission spectroscopy. The peak width or inverse lifetime of the excitation displays a linear temperature dependence, independent of binding energy, for small energies, and a linear energy dependence, independent of temperature, for large binding energies. This behavior is unaffected by the superconducting transition, which is an indication that the nodal states play no role in the superconductivity. Temperature-dependent scaling suggests that the system displays quantum critical behavior.
382 citations