Review of Scientific Instruments
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Utilization of synchrotron radiation in the far-infrared region (invited) A spectroscopic system for the far-infrared region is described which was constructed at beamline BL6A1 of the UVSOR facility at the Institute for Molecular Science (Okazaki) and has been used since 1986. Intensity measurements at UVSOR proved that synchrotron radiation is a very bright source compared with a blackbody source throughout the entire far-infrared region. To demonstrate the advantages of synchrotron radiation in the far-infrared region, results on a reflection measurement of a small specimen and an absorption measurement under high pressure using a diamond anvil cell are shown. From the measurement of the shift of the TO phonon energy of KI with pressure, the mode Gruneisen parameter at room temperature was determined to be 1.70.
Review of Scientific Instruments - Tập 60 Số 7 - Trang 1680-1685 - 1989
A new compact 60 kV Mott polarimeter for spin polarized electron spectroscopy A compact 60 kV Mott polarimeter has been constructed, tested, and calibrated especially for the local analysis of surface and two-dimension magnetism by means of electron spectroscopy with spin resolution. The use of construction combining spherical accelerating field with the absence of retarding potential after electron scattering provides low sensitivity of the polarimeter to movements of the analyzed electron beam and changes in its diameter. Special silicon surface-barrier detectors with large electron-optical acceptance provide efficiency ∈(≡Seff2×I/I0) about ≈2.5×10−4. The unique fast electronics allow to work with maximum count rate of detected electrons up to 5×106 counts/s. As a result, there is the possibility to calibrate the polarimeter (to calculate the effective Sherman function Seff) by extrapolation of the measured asymmetry to the high level of discrimination. This instrument is compact, fully UHV compatible and may be used in other fields of solid state physics, atomic physics, and physics of high energies.
Review of Scientific Instruments - Tập 68 Số 12 - Trang 4385-4389 - 1997
Monochromator beamline for FLASH The design of a high resolution monochromator for the vacuum ultraviolet free electron laser at Hamburg (FLASH), DESY, is described. The monochromator is constructed as a plane grating monochromator using collimated light. Modifications have been made to take into account the free electron laser (FEL) beam characteristics, in particular, the extremely high peak power density of the radiation. Ray tracing simulations yield a resolving power in the range of 10 000–70 000 depending on the photon energy and the grating in use. Our monochromator is equipped with a 200line∕mm grating for the energy range of 20–200eV—the operation regime of FLASH—and a high resolution 1200line∕mm grating for the energy range of 100–600eV, covering the higher harmonic radiation of the FEL.
Review of Scientific Instruments - Tập 77 Số 11 - 2006
Microspectroscopy and imaging using a delay line detector in time-of-flight photoemission microscopy A method for microspectroscopy and energy-selective imaging using a special photoemission electron microscope (PEEM) is presented. A modified commercial PEEM was combined with a delay line device as x, y, t detector serving as the basic arrangement for spectromicroscopy. One can measure the time of flight of the electrons passing a drift section in order to analyze the energy distribution of photoelectrons in PEEM. The time of flight is referenced to the time structure of the synchrotron radiation from an electron storage ring. At electron kinetic energies of less than 20 eV within the drift region a spatial resolution of about 100 nm has been obtained. Fast counting electronics (instead of a camera) delivers an image for real-time monitoring on an oscilloscope screen or for image acquisition by a computer. A time resolution of about 500 ps has been obtained with the potential of further improvement. The spatial resolution of the delay line detector is about 50 μm in the image plane corresponding to 1000 pixels in the image diagonal. Direct photoemission from the W-4f core level of a W(110) single-crystal sample was observed at several photon energies. The W-4f fine-structure splitting of 2.3 eV could be well resolved at a pass energy around 40 eV through the drift region.
Review of Scientific Instruments - Tập 72 Số 10 - Trang 3968-3974 - 2001
A high-efficiency spin-resolved photoemission spectrometer combining time-of-flight spectroscopy with exchange-scattering polarimetry We describe a spin-resolved electron spectrometer capable of uniquely efficient and high energy resolution measurements. Spin analysis is obtained through polarimetry based on low-energy exchange scattering from a ferromagnetic thin-film target. This approach can achieve a similar analyzing power (Sherman function) as state-of-the-art Mott scattering polarimeters, but with as much as 100 times improved efficiency due to increased reflectivity. Performance is further enhanced by integrating the polarimeter into a time-of-flight (TOF) based energy analysis scheme with a precise and flexible electrostatic lens system. The parallel acquisition of a range of electron kinetic energies afforded by the TOF approach results in an order of magnitude (or more) increase in efficiency compared to hemispherical analyzers. The lens system additionally features a 90° bandpass filter, which by removing unwanted parts of the photoelectron distribution allows the TOF technique to be performed at low electron drift energy and high energy resolution within a wide range of experimental parameters. The spectrometer is ideally suited for high-resolution spin- and angle-resolved photoemission spectroscopy (spin-ARPES), and initial results are shown. The TOF approach makes the spectrometer especially ideal for time-resolved spin-ARPES experiments.
Review of Scientific Instruments - Tập 81 Số 5 - 2010
Rapid high-resolution spin- and angle-resolved photoemission spectroscopy with pulsed laser source and time-of-flight spectrometer A high-efficiency spin- and angle-resolved photoemission spectroscopy (spin-ARPES) spectrometer is coupled with a laboratory-based laser for rapid high-resolution measurements. The spectrometer combines time-of-flight (TOF) energy measurements with low-energy exchange scattering spin polarimetry for high detection efficiencies. Samples are irradiated with fourth harmonic photons generated from a cavity-dumped Ti:sapphire laser that provides high photon flux in a narrow bandwidth, with a pulse timing structure ideally matched to the needs of the TOF spectrometer. The overall efficiency of the combined system results in near-EF spin-resolved ARPES measurements with an unprecedented combination of energy resolution and acquisition speed. This allows high-resolution spin measurements with a large number of data points spanning multiple dimensions of interest (energy, momentum, photon polarization, etc.) and thus enables experiments not otherwise possible. The system is demonstrated with spin-resolved energy and momentum mapping of the L-gap Au(111) surface states, a prototypical Rashba system. The successful integration of the spectrometer with the pulsed laser system demonstrates its potential for simultaneous spin- and time-resolved ARPES with pump-probe based measurements.
Review of Scientific Instruments - Tập 84 Số 9 - 2013
High-efficiency spin polarimetry by very-low-energy electron scattering from Fe(100) for spin-resolved photoemission We describe concept, design, and performance of a novel spin polarimeter based on spin-dependent specular reflection of electrons from a Fe(100) surface. The Fe surface is prepared as an ultrathin film on Ag(100). By tuning the energy of the electrons to a critical point in the Fe band structure, a large spin asymmetry combined with a large scattering efficiency is achieved. The polarimeter yields a figure of merit up to 10−2 for the best Fe(100) surfaces.
Review of Scientific Instruments - Tập 73 Số 3 - Trang 1229-1234 - 2002
A compact electron-spin-polarization manipulator A compact electron-spin-polarization manipulator is described which allows one to align the polarization in any desired direction in space. The system delivers a focused electron beam of typically 3–5 keV. Its application in spin-polarized low-energy electron microscopy for the study of magnetic domain structures is briefly illustrated.
Review of Scientific Instruments - Tập 66 Số 4 - Trang 2861-2864 - 1995
Temperature dependence of the fluorescence lifetime in Pr3+:ZBLAN glass for fiber optic thermometry An analysis of the fluorescence decay behavior of Pr 3+ in ZBLAN glass, at different concentrations, has been undertaken, for applications of the material to fiber optic thermometry. The study has shown that with the temperature increase, the measured lifetimes of the fluorescence emission from the Pr 3+ doped glass are also seen to increase slowly. The results obtained are found not to support a simple two-level model based on the thermalization of the states involved but a new three-level model that has been introduced can explain the observed results in a very satisfactory way. The application of the work in optical thermometry is discussed and comparisons with other systems are made.
Review of Scientific Instruments - Tập 68 Số 9 - Trang 3447-3451 - 1997
Microwave Discharge Source for Atomic and Molecular Beam Production An atomic and molecular beam source is described which overcomes disadvantages present in earlier types of microwave discharge sources. The source uses a resonant coaxial line which requires no tuning adjustments inside the vacuum system. No water cooling is required. The source operates efficiently over a wide discharge pressure range and for many different discharge gases.
Review of Scientific Instruments - Tập 39 Số 8 - Trang 1171-1172 - 1968
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