Collision‐energy/electron‐energy resolved two‐dimensional study of Penning ionization of Ar by He metastable atoms 23Sand 21S

1996 ◽  
Vol 105 (17) ◽  
pp. 7536-7542 ◽  
Author(s):  
Koichi Ohno ◽  
Hideo Yamakado ◽  
Tetsuji Ogawa ◽  
Toshiaki Yamata
Keyword(s):  
Electron Energy ◽  
Collision Energy ◽  
Energy Electron ◽  
Two Dimensional ◽  
Penning Ionization

Scanning Low-Energy Electron Diffraction Microscopy Combined with Scanning Tunnling Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 302-303
Author(s):  
Takeo Ichinokawa
Keyword(s):  
Electron Diffraction ◽  
Electron Energy ◽  
High Vacuum ◽  
Low Energy ◽  
Energy Electron ◽  
Scanning Tunneling ◽  
Two Dimensional ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Auger Microscopy

A ultra-high vacuum scanning electron microscope (UHV-SEM) with a field emission gun (FEG) has been operated in an energy range of from 100 eV to 3 keV. A new technique of scanning low energy electron diffraction (LEED) microscopy has been added to the other techniques: scanning Auger microscopy (SAM), secondary electron microscopy, electron energy loss microscopy and the others available for the UHV-SEM. In addition to scanning LEED microscopy, a scanning tunneling microscope (STM) has been installed in the UHV-SEM-.The combination of STM with SEM covers a wide magnification range from 105 to 107 and is very effective for observation of surface structures with a high resolution of about 1 Å.A UHV-FEG-SEM is equipped in a chamber in which the vacuum is better than 2×10-10 Torr. A movable cylindrical mirror analyzer (CMA), a two dimensional detector of diffracted LEED beams, an ion gun and a deposition source are installed in this chamber. The concept of the scanning LEED microscope is comprised of two steps: (1) the formation of a selected area LEED pattern and (2) the generation of raster images with information contained in the diffraction pattern. In the present experiment, the LEED detector assembly shown in Fig.l has been used; it consists of two hemisherical grids, a two-stage channel-plate amplifier and a position-sensitive detector. The selection of one (or more) diffracted beam is performed electronically by a window using the two-dimensional analogue comparators. The intensity of a particular beam selected by the window modulates the brightness of the scanning image and a dark field image sensitive to the surface structure is formed. The experimental spatial resolutions of 150 Å and 500 Å have been attained at the primary electron energy 1 keV and 250 eV, respectively.

Comparison of Calculated and Recorded Electron Energy-Loss Spectra of Aluminium and Carbon

1990 ◽  
Vol 48 (2) ◽  
pp. 64-65
Author(s):  
L. Reimer ◽  
R. Oelgeklaus
Keyword(s):  
Fourier Transform ◽  
Energy Loss ◽  
Electron Energy ◽  
Rotational Symmetry ◽  
Mean Free Path ◽  
Single Scattering ◽  
Specimen Thickness ◽  
Two Dimensional ◽  
Image Position ◽  
Electron Energy Loss

Quantitative electron energy-loss spectroscopy (EELS) needs a correction for the limited collection aperture α and a deconvolution of recorded spectra for eliminating the influence of multiple inelastic scattering. Reversely, it is of interest to calculate the influence of multiple scattering on EELS. The distribution f(w,θ,z) of scattered electrons as a function of energy loss w, scattering angle θ and reduced specimen thickness z=t/Λ (Λ=total mean-free-path) can either be recorded by angular-resolved EELS or calculated by a convolution of a normalized single-scattering function ϕ(w,θ). For rotational symmetry in angle (amorphous or polycrystalline specimens) this can be realised by the following sequence of operations :(1)where the two-dimensional distribution in angle is reduced to a one-dimensional function by a projection P, T is a two-dimensional Fourier transform in angle θ and energy loss w and the exponent -1 indicates a deprojection and inverse Fourier transform, respectively.

scholarly journals Chemical identification through two-dimensional electron energy-loss spectroscopy

2020 ◽  
Vol 6 (28) ◽  
pp. eabb4713
Author(s):  
Renwen Yu ◽  
F. Javier García de Abajo
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Electronic Device ◽  
Theoretical Calculations ◽  
Chemical Species ◽  
High Sensitivity ◽  
Two Dimensional ◽  
Excitation Spectra ◽  
Electron Energy Loss

We explore a disruptive approach to nanoscale sensing by performing electron energy loss spectroscopy through the use of low-energy ballistic electrons that propagate on a two-dimensional semiconductor. In analogy to free-space electron microscopy, we show that the presence of analyte molecules in the vicinity of the semiconductor produces substantial energy losses in the electrons, which can be resolved by energy-selective electron injection and detection through actively controlled potential gates. The infrared excitation spectra of the molecules are thereby gathered in this electronic device, enabling the identification of chemical species with high sensitivity. Our realistic theoretical calculations demonstrate the superiority of this technique for molecular sensing, capable of performing spectral identification at the zeptomol level within a microscopic all-electrical device.

scholarly journals Low energy electron energy-loss spectroscopy of CF3X (X=Cl,Br)

2007 ◽  
Vol 126 (2) ◽  
pp. 024303 ◽  
Author(s):  
M. Hoshino ◽  
K. Sunohara ◽  
C. Makochekanwa ◽  
L. Pichl ◽  
H. Cho ◽  
...  
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Low Energy ◽  
Energy Electron ◽  
Low Energy Electron ◽  
Electron Energy Loss
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