scholarly journals A vacuum ultraviolet laser with a submicrometer spot for spatially resolved photoemission spectroscopy

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yuanhao Mao ◽  
Dong Zhao ◽  
Shen Yan ◽  
Hongjia Zhang ◽  
Juan Li ◽  
...  
Keyword(s):  
Light Source ◽  
Vacuum Ultraviolet ◽  
Spherical Aberration ◽  
Focal Length ◽  
Laser System ◽  
Photoemission Spectroscopy ◽  
Beam Spot ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Spatially Resolved ◽  
Metal Grating

AbstractVacuum ultraviolet (VUV) lasers have demonstrated great potential as the light source for various spectroscopies, which, if they can be focused into a small beam spot, will not only allow investigation of mesoscopic materials and structures but also find application in the manufacture of nano-objects with excellent precision. In this work, we report the construction of a 177 nm VUV laser that can achieve a record-small (~0.76 μm) focal spot at a long focal length (~45 mm) by using a flat lens without spherical aberration. The size of the beam spot of this VUV laser was tested using a metal grating and exfoliated graphene flakes, and we demonstrated its application in a fluorescence spectroscopy study on pure and Tm3+-doped NaYF4 microcrystals, revealing a new emission band that cannot be observed in the traditional up-conversion process. In addition, this laser system would be an ideal light source for spatially and angle-resolved photoemission spectroscopy.

scholarly journals Tunable vacuum ultraviolet laser based spectrometer for angle resolved photoemission spectroscopy

2014 ◽  
Vol 85 (3) ◽  
pp. 033902 ◽  
Author(s):  
Rui Jiang ◽  
Daixiang Mou ◽  
Yun Wu ◽  
Lunan Huang ◽  
Colin D. McMillen ◽  
...  
Keyword(s):  
Vacuum Ultraviolet ◽  
Photoemission Spectroscopy ◽  
Ultraviolet Laser ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Vacuum Ultraviolet Laser

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.

Performance of the BL03U beamline at SSRF

2020 ◽  
Vol 27 (5) ◽  
pp. 1388-1394
Author(s):  
Z. P. Sun ◽  
Z. H. Liu ◽  
Z. T. Liu ◽  
W. L. Liu ◽  
F. Y. Zhang ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Energy Range ◽  
Photon Energy ◽  
Vacuum Ultraviolet ◽  
Resolving Power ◽  
Photon Energy Range ◽  
Photoemission Spectroscopy ◽  
Theoretical Estimation ◽  
Shanghai Synchrotron Radiation Facility ◽  
Angle Resolved Photoemission Spectroscopy

The vacuum ultraviolet beamline BL03U with a photon energy range from 7 eV upwards has been constructed at the 3.5 GeV Shanghai Synchrotron Radiation Facility. Equipped with an APPLE-Knot undulator, this beamline is dedicated to angle-resolved photoemission spectroscopy. An energy-resolving power of higher than 4.6 × 104 has been achieved in the photon energy range 21.6–48 eV, which is almost the same as the theoretical estimation.

Resolution Attainable With the Present Day STEM

1973 ◽  
Vol 31 ◽  
pp. 230-231 ◽  
Author(s):  
J. S. Wall ◽  
J. P. Langmore ◽  
H. Isaacson ◽  
A. V. Crewe
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Incident Beam ◽  
Scanning Transmission Electron Microscope ◽  
Aperture Size ◽  
Magnetic Lens ◽  
Peak Intensity ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Half Angle

The scanning transmission electron microscope (STEM) constructed by the authors employs a field emission gun and a 1.15 mm focal length magnetic lens to produce a probe on the specimen. The aperture size is chosen to allow one wavelength of spherical aberration at the edge of the objective aperture. Under these conditions the profile of the focused spot is expected to be similar to an Airy intensity distribution with the first zero at the same point but with a peak intensity 80 per cent of that which would be obtained If the lens had no aberration. This condition is attained when the half angle that the incident beam subtends at the specimen, 𝛂 = (4𝛌/Cs)¼

Improvements in the electron probe forming capabilities and x-ray hole counts in the Philips TEM

1983 ◽  
Vol 41 ◽  
pp. 376-377
Author(s):  
Richard L. McConville
Keyword(s):  
Field Strength ◽  
Electron Probe ◽  
Spherical Aberration ◽  
Focal Length ◽  
Objective Lens ◽  
Parallel Beam ◽  
Tilt Axis ◽  
X Ray ◽  
Small Probe ◽  
Specimen Height

A second generation twin lens has been developed. This symmetrical lens with a wider bore, yet superior values of chromatic and spherical aberration for a given focal length, retains both eucentric ± 60° tilt movement and 20°x ray detector take-off angle at 90° to the tilt axis. Adjust able tilt axis height, as well as specimen height, now ensures almost invariant objective lens strengths for both TEM (parallel beam conditions) and STEM or nano probe (focused small probe) modes.These modes are selected through use of an auxiliary lens situ ated above the objective. When this lens is on the specimen is illuminated with a parallel beam of electrons, and when it is off the specimen is illuminated with a focused probe of dimensions governed by the excitation of the condenser 1 lens. Thus TEM/STEM operation is controlled by a lens which is independent of the objective lens field strength.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

A High Resolution Scanning Microscope

1968 ◽  
Vol 26 ◽  
pp. 356-357
Author(s):  
A. V. Crewe ◽  
J. Wall ◽  
L. M. Welter
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Spherical Aberration ◽  
Focal Length ◽  
Spot Size ◽  
Emission Source ◽  
Field Of View ◽  
Scanning Microscope ◽  
Magnetic Lens ◽  
High Quality

A scanning microscope using a field emission source has been described elsewhere. This microscope has now been improved by replacing the single magnetic lens with a high quality lens of the type described by Ruska. This lens has a focal length of 1 mm and a spherical aberration coefficient of 0.5 mm. The final spot size, and therefore the microscope resolution, is limited by the aberration of this lens to about 6 Å.The lens has been constructed very carefully, maintaining a tolerance of + 1 μ on all critical surfaces. The gun is prealigned on the lens to form a compact unit. The only mechanical adjustments are those which control the specimen and the tip positions. The microscope can be used in two modes. With the lens off and the gun focused on the specimen, the resolution is 250 Å over an undistorted field of view of 2 mm. With the lens on,the resolution is 20 Å or better over a field of view of 40 microns. The magnification can be accurately varied by attenuating the raster current.

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