Absolute determination of surface atomic concentration by reflection electron energy-loss spectroscopy

1988 ◽  
Vol 46 ◽  
pp. 502-503
Author(s):  
Z. L. Wang ◽  
R.F. Egerton
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Crystal Surface ◽  
Resonance Condition ◽  
Atomic Concentration ◽  
Transmission Electron ◽  
Reflection Electron Microscopy ◽  
Image Position ◽  
Electron Energy Loss

Reflection electron energy-loss spectroscopy (REELS) has been demonstrated as a useful technique for analyzing the structure of crystal surfaces. It is a combination of EELS with reflection electron microscopy (REM) performed in a transmission electron microscope. Here, we suggest a basic theory and experiment which enable REELS to determine absolutely the atomic concentration (atoms per unit volume) at a crystal surface.In the RHEED case, not all the incident electrons will travel an equal distance within the sample (fig. 1A). Under the surface-resonance condition, the incident electrons are propagating parallel or nearly parallel to the crystal surface. Then a mean travelling distance (MTD) D can be defined, along which the excitation of atomic inner shells is equivalent to the total excitation of the atomic inner shells in the dynamical scattering (fig. IB). It can be found from the analysis of experimental data as:(1)

scholarly journals Ultrafast electron energy-loss spectroscopy in transmission electron microscopy

MRS Bulletin ◽  
2018 ◽  
Vol 43 (7) ◽  
pp. 497-503 ◽  
Author(s):  
Enrico Pomarico ◽  
Ye-Jin Kim ◽  
F. Javier García de Abajo ◽  
Oh-Hoon Kwon ◽  
Fabrizio Carbone ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Transmission Electron ◽  
Image Position ◽  
Electron Energy Loss

Abstract

A Poor Man’s Approach to Semi-Quantitative Analysis with Electron Energy Loss Spectroscopy

1980 ◽  
Vol 38 ◽  
pp. 110-111
Author(s):  
M. Isaacson
Keyword(s):  
Quantitative Analysis ◽  
Energy Loss ◽  
Electron Energy ◽  
Cross Section ◽  
Electron Energy Loss Spectroscopy ◽  
Excitation Cross Section ◽  
Incident Electron ◽  
Integral Cross Section ◽  
Image Position ◽  
Electron Energy Loss

In an earlier paper1 it was found that to a good approximation, the efficiency of collection of electrons that had lost energy due to an inner shell excitation could be written as where σE was the total excitation cross-section and σE(θ, Δ) was the integral cross-section for scattering within an angle θ and with an energy loss up to an energy Δ from the excitation edge, EE. We then obtained: where , with P being the momentum of the incident electron of velocity v. The parameter r was due to the assumption that d2σ/dEdΩ∞E−r for energy loss E. In reference 1 it was assumed that r was a constant.

Investigation of Switching Mechanism in HfO2-Based Oxide Resistive Memories by In-Situ Transmission Electron Microscopy and Electron Energy Loss Spectroscopy

2017 ◽  
Author(s):  
T. Dewolf ◽  
D. Cooper ◽  
N. Bernier ◽  
V. Delaye ◽  
A. Grenier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Hafnium Dioxide ◽  
Switching Mechanism ◽  
Transmission Electron ◽  
Electron Energy Loss

Abstract Forming and breaking a nanometer-sized conductive area are commonly accepted as the physical phenomenon involved in the switching mechanism of oxide resistive random access memories (OxRRAM). This study investigates a state-of-the-art OxRRAM device by in-situ transmission electron microscopy (TEM). Combining high spatial resolution obtained with a very small probe scanned over the area of interest of the sample and chemical analyses with electron energy loss spectroscopy, the local chemical state of the device can be compared before and after applying an electrical bias. This in-situ approach allows simultaneous TEM observation and memory cell operation. After the in-situ forming, a filamentary migration of titanium within the dielectric hafnium dioxide layer has been evidenced. This migration may be at the origin of the conductive path responsible for the low and high resistive states of the memory.

Electron Energy-Loss Spectroscopy (EELS) of Fe-Bearing Olivine and Laihunite (an Oxidized Olivine)

2000 ◽  
Vol 6 (S2) ◽  
pp. 208-209
Author(s):  
Huifang Xu ◽  
Pingqiu Fu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Structure Refinement ◽  
Iron Formation ◽  
Transmission Electron ◽  
Electron Energy Loss

Laihunite that has distorted olivine-type structure with ferric and ferrous irons and ordered distribution of vacancies was first discovered in a high-grade metamorphosed banded iron formation (BIF) [1, 2]. The laihunite coexisting with fayalite (Fe-olivine), magnetite, quartz, ferrosilite, garnet and hedenbergite, formed in the process of oxidation of fayalite [2, 3]. The structure refinement of 1-layer laihunite shows P21/b symmetry and ordered distribution of vacancies in half M1 sites of olivine structure [2, 3]. Early high-resolution transmission electron microscopy (HRTEM) study and HRTEM image simulation of the 1-layer laihunite verified the structure refinement [4].Specimens of weakly oxidized fayalite and laihunite containing fayalite islands collected from Xiaolaihe and Menjiagou of Liaoning Province, NE China, have been studied using selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS), and X-ray energy-dispersive spectroscopy.

Analysis of AlxGa1-xN nanowires through simulated methods of scanning transmission electron microscopy and electron energy-loss spectroscopy

2013 ◽  
Vol 6 (1) ◽  
Author(s):  
R. Kumar ◽  
P.J. Phillips ◽  
R.F. Klie
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Energy Loss

AlxGa1-xN nanowires have promising applications in ultraviolet light emitting diodes (LEDs). However, these nanowires are not typical p-n junction semiconductors, but rather rely on varying concentrations of Al versus Ga to produce electron hole pairs. More information on the atomic structure is needed to better understand the properties of these nanowires. In this study, AlxGa1-xN nanowires were imaged using scanning transmission electron microscopy (STEM) and compared to computer simulated STEM images to obtain physical information on the nanowires. Electron energy-loss spectroscopy (EELS) and FEFF9 computer simulations were also performed to better understand the structural and chemical properties of the nanowires. Results from these simulations showed that changes in the chemical ordering of the nanowires were responsible for changes in intensity and resolution in the images. These intensity and resolution trends were not a result of interface effects. This will help to further characterize nanowires in the future.

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