Inner shell electron-energy loss spectroscopy of some heterocyclic molecules

1986 ◽  
Vol 64 (6) ◽  
pp. 1145-1155 ◽  
Author(s):  
D C Newbury ◽  
I Ishii ◽  
A P Hitchcock
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Small Angle ◽  
Electric Dipole ◽  
Electron Energy Loss Spectroscopy ◽  
Bond Lengths ◽  
Heterocyclic Molecules ◽  
Valence States ◽  
Dipole Scattering ◽  
Electron Energy Loss

The carbon K-shell spectra of gaseous furan, pyrrole, tetrahydrofuran, pyrrolidine, tetrahydropyran, and piperidine have been recorded by electron energy loss spectroscopy (ISEELS) under electric dipole scattering conditions (2.5 keV impact, small angle.) The spectra are dominated by transitions to unoccupied valence states of π and σ symmetry. Features attributed to transitions to π*(CH2) levels are consistently observed below the ionization threshold in the spectra of the saturated species. the positions of continuum features are generally in agreement with a previously documented correlation with bond lengths. Additional weak continuum features are observed in the smaller saturated heterocyclic species which are ascribed to delocalized σ* states.

Fast Mapping of the Cobalt-Valence State in Ba0.5Sr0.5Co0.8Fe0.2O3-dby Electron Energy Loss Spectroscopy

2013 ◽  
Vol 19 (6) ◽  
pp. 1595-1605 ◽  
Author(s):  
Philipp Müller ◽  
Matthias Meffert ◽  
Heike Störmer ◽  
Dagmar Gerthsen
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Valence State ◽  
Hexagonal Phase ◽  
Fast Method ◽  
White Line ◽  
Valence States ◽  
Electron Energy Loss

AbstractA fast method for determination of the Co-valence state by electron energy loss spectroscopy in a transmission electron microscope is presented. We suggest the distance between the Co-L3and Co-L2white-lines as a reliable property for the determination of Co-valence states between 2+ and 3+. The determination of the Co-L2,3white-line distance can be automated and is therefore well suited for the evaluation of large data sets that are collected for line scans and mappings. Data with a low signal-to-noise due to short acquisition times can be processed by applying principal component analysis. The new technique was applied to study the Co-valence state of Ba0.5Sr0.5Co0.8Fe0.2O3-d(BSCF), which is hampered by the superposition of the Ba-M4,5white-lines on the Co-L2,3white-lines. The Co-valence state of the cubic BSCF phase was determined to be 2.2+ (±0.2) after annealing for 100 h at 650°C, compared to an increased valence state of 2.8+ (±0.2) for the hexagonal phase. These results support models that correlate the instability of the cubic BSCF phase with an increased Co-valence state at temperatures below 840°C.

Role of multiple dipole scattering in high-resolution electron-energy-loss spectroscopy

1994 ◽  
Vol 49 (17) ◽  
pp. 11613-11618 ◽  
Author(s):  
Li-Ming Yu ◽  
P. A. Thiry ◽  
A. Degiovanni ◽  
Th. Conard ◽  
R. Caudano
Keyword(s):  
High Resolution ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Resolution Electron ◽  
Dipole Scattering ◽  
Electron Energy Loss

Shifts in Valence States in Bimetallic MXenes Revealed by Electron Energy-Loss Spectroscopy (EELS)

2D Materials ◽  
2022 ◽  
Author(s):  
Alexandre C. Foucher ◽  
Meikang Han ◽  
Christopher E. Shuck ◽  
Kathleen Maleski ◽  
Yury Gogotsi ◽  
...  
Keyword(s):  
Solid Solution ◽  
Energy Loss ◽  
Electron Energy ◽  
Oxidation State ◽  
Electron Energy Loss Spectroscopy ◽  
Valence State ◽  
Fine Tuning ◽  
Valence States ◽  
The Impact ◽  
Electron Energy Loss

Abstract MXenes are an emergent class of two-dimensional materials with a very wide spectrum of promising applications. The synthesis of multiple MXenes, specifically solid-solution MXenes, allows fine tuning of their properties, expands their range of applications, and leads to enhanced performance. The functionality of solid-solution MXenes is closely related to the valence state of their constituents: transition metals, oxygen, carbon, and nitrogen. However, the impact of changes in the oxidation state of elements in MXenes is not well understood. In this work, three interrelated solid-solution MXene systems (Ti2-yNbyCTx, Nb2-yVyCTx, and Ti2-yVyCTx) were investigated with scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS) to determine the localized valence states of metals at the nanoscale. The analysis demonstrates changes in the electronic configuration of V upon modification of the overall composition and within individual MXene flakes. These shifts of oxidation state can explain the nonlinear optical and electronic features of solid-solution MXenes. Vanadium appears to be particularly sensitive to modification of the valence state, while titanium maintains the same oxidation state in Ti-Nb and Ti-V MXenes, regardless of stoichiometry. The study also explains Nb's influential role in the previously observed electronic properties in the Nb-V and Nb-Ti systems.

Determination of manganese valence states in (Mn3+, Mn4+) minerals by electron energy-loss spectroscopy

2010 ◽  
Vol 95 (11-12) ◽  
pp. 1741-1746 ◽  
Author(s):  
S. Zhang ◽  
K. J. T. Livi ◽  
A.-C. Gaillot ◽  
A. T. Stone ◽  
D. R. Veblen
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Valence States ◽  
Manganese Valence ◽  
Electron Energy Loss

Data Acquisition and Handling Unit for a Quantitative Use of Electron Energy Loss Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 232-233 ◽  
Author(s):  
P. Trebbia ◽  
P. Ballongue ◽  
C. Colliex
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Single Channel ◽  
Detection System ◽  
Surface Barrier ◽  
Solid State Detector ◽  
Electrostatic Mirror ◽  
Electron Energy Loss

An effective use of electron energy loss spectroscopy for chemical characterization of selected areas in the electron microscope can only be achieved with the development of quantitative measurements capabilities.The experimental assembly, which is sketched in Fig.l, has therefore been carried out. It comprises four main elements.The analytical transmission electron microscope is a conventional microscope fitted with a Castaing and Henry dispersive unit (magnetic prism and electrostatic mirror). Recent modifications include the improvement of the vacuum in the specimen chamber (below 10-6 torr) and the adaptation of a new electrostatic mirror.The detection system, similar to the one described by Hermann et al (1), is located in a separate chamber below the fluorescent screen which visualizes the energy loss spectrum. Variable apertures select the electrons, which have lost an energy AE within an energy window smaller than 1 eV, in front of a surface barrier solid state detector RTC BPY 52 100 S.Q. The saw tooth signal delivered by a charge sensitive preamplifier (decay time of 5.10-5 S) is amplified, shaped into a gaussian profile through an active filter and counted by a single channel analyser.

Trends in Electron Energy Loss Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 228-229
Author(s):  
C. Colliex ◽  
P. Trebbia
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Materials Science ◽  
Analytical Technique ◽  
Recent Developments ◽  
Quantitative Results ◽  
Electron Microscopes ◽  
Electron Energy Loss ◽  
Primary Electrons

The physical foundations for the use of electron energy loss spectroscopy towards analytical purposes, seem now rather well established and have been extensively discussed through recent publications. In this brief review we intend only to mention most recent developments in this field, which became available to our knowledge. We derive also some lines of discussion to define more clearly the limits of this analytical technique in materials science problems.The spectral information carried in both low ( 0<ΔE<100eV ) and high ( >100eV ) energy regions of the loss spectrum, is capable to provide quantitative results. Spectrometers have therefore been designed to work with all kinds of electron microscopes and to cover large energy ranges for the detection of inelastically scattered electrons (for instance the L-edge of molybdenum at 2500eV has been measured by van Zuylen with primary electrons of 80 kV). It is rather easy to fix a post-specimen magnetic optics on a STEM, but Crewe has recently underlined that great care should be devoted to optimize the collecting power and the energy resolution of the whole system.

Signal/Noise Ratio and Elemental Detectivity by Eels

1982 ◽  
Vol 40 ◽  
pp. 488-489
Author(s):  
R. F. Egerton
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Elemental Analysis ◽  
Electron Energy Loss Spectroscopy ◽  
Emission Spectroscopy ◽  
X Ray ◽  
Signal Noise ◽  
Characteristic Signal ◽  
Noise Ratio ◽  
Electron Energy Loss

An important parameter governing the sensitivity and accuracy of elemental analysis by electron energy-loss spectroscopy (EELS) or by X-ray emission spectroscopy is the signal/noise ratio of the characteristic signal.

Quantitative Electron Energy Loss Mapping

1985 ◽  
Vol 43 ◽  
pp. 404-405
Author(s):  
R.D. Leapman ◽  
C.R. Swyt
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Elemental Concentration ◽  
Core Loss ◽  
Elemental Distribution ◽  
Electron Energy Loss

The intensity of a characteristic electron energy loss spectroscopy (EELS) image does not, in general, directly reflect the elemental concentration. In fact, the raw core loss image can give a misleading impression of the elemental distribution. This is because the measured core edge signal depends on the amount of plural scattering which can vary significantly from region to region in a sample. Here, we show how the method for quantifying spectra due to Egerton et al. can be extended to maps.

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