Fine structure of inner shell electron energy loss edges of manganese oxides

1989 ◽  
Vol 47 ◽  
pp. 392-393
Author(s):  
James H. Paterson ◽  
Ondrej L. Krivanek ◽  
Helmut R. Poppa
Keyword(s):  
Fine Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Manganese Oxides ◽  
Scanning Transmission Electron Microscope ◽  
Parallel Detection ◽  
Scanning Transmission ◽  
And Performance ◽  
Electron Energy Loss

Rask et al. showed that electron energy loss spectroscopy (EELS) may be used to identify oxidation states of polyvalent cations. For the case of manganese, differences in oxidation state are reflected in the shape and position of the edges in the EELS spectrum due to inelastic scattering of incident electrons by the inner shells of manganese and oxygen. We have used a scanning transmission electron microscope (STEM) with a cold field emission gun (FEG) and a parallel-detection EELS system to re-investigate the variations in energy loss fine structure of EELS spectra of various manganese oxides with a significantly improved energy resolution.Spectra were recorded at 100 kV using a VG HB501 STEM with post-specimen lenses, and a Galan Model 666 parallel-detection electron energy loss spectrometer. The operation and performance of this system are discussed elsewhere in these proceedings. For the inner shell edges, the energy dispersion produced by the spectrometer was set to give 0.05 eV per channel. so that a complete spectrum of 1024 channels sampled a range of energy loss of 50 eV. The energy resolution, of the order of 0.4 eV, was therefore not limited by the spatial resolution of the photodiode array in the spectrometer. The oxygen K and manganese L2,3 edges were recorded separately.

Parallel Detection of Electron Energy Loss Spectra in Direct Mode

1990 ◽  
Vol 48 (2) ◽  
pp. 82-83
Author(s):  
Eckhard Quandt ◽  
Stephan laBarré ◽  
Andreas Hartmann ◽  
Heinz Niedrig
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Large Angle ◽  
Maximum Energy ◽  
Semiconductor Detectors ◽  
Parallel Detection ◽  
Photodiode Arrays ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Due to the development of semiconductor detectors with high spatial resolution -- e.g. charge coupled devices (CCDs) or photodiode arrays (PDAs) -- the parallel detection of electron energy loss spectra (EELS) has become an important alternative to serial registration. Using parallel detection for recording of energy spectroscopic large angle convergent beam patterns (LACBPs) special selected scattering vectors and small detection apertures lead to very low intensities. Therefore the very sensitive direct irradiation of a cooled linear PDA instead of the common combination of scintillator, fibre optic, and semiconductor has been investigated. In order to obtain a sufficient energy resolution the spectra are optionally magnified by a quadrupole-lens system.The detector used is a Hamamatsu S2304-512Q linear PDA with 512 diodes and removed quartz-glas window. The sensor size is 13 μm ∗ 2.5 mm with an element spacing of 25 μm. Along with the dispersion of 3.5 μm/eV at 40 keV the maximum energy resolution is limited to about 7 eV, so that a magnification system should be attached for experiments requiring a better resolution.

Simulation of Probe Position-Dependent Electron Energy-Loss Fine Structure

2014 ◽  
Vol 20 (3) ◽  
pp. 784-797 ◽  
Author(s):  
Mark P. Oxley ◽  
Myron D. Kapetanakis ◽  
Micah P. Prange ◽  
Maria Varela ◽  
Stephen J. Pennycook ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Energy Loss ◽  
Electron Energy ◽  
Density Functional ◽  
Scanning Transmission Electron Microscope ◽  
Probe Position ◽  
Functional Theory ◽  
Edge Structure ◽  
Scanning Transmission ◽  
Electron Energy Loss

AbstractWe present a theoretical framework for calculating probe-position-dependent electron energy-loss near-edge structure for the scanning transmission electron microscope by combining density functional theory with dynamical scattering theory. We show how simpler approaches to calculating near-edge structure fail to include the fundamental physics needed to understand the evolution of near-edge structure as a function of probe position and investigate the dependence of near-edge structure on probe size. It is within this framework that density functional theory should be presented, in order to ensure that variations of near-edge structure are truly due to local electronic structure and how much from the diffraction and focusing of the electron beam.

ELECTRON ENERGY LOSS SPECTROSCOPY AND ANNULAR DARK FIELD IMAGING AT A NANOMETER RESOLUTION IN A SCANNING TRANSMISSION ELECTRON MICROSCOPE

2000 ◽  
Vol 07 (04) ◽  
pp. 475-494 ◽  
Author(s):  
O. STÉPHAN ◽  
A. GLOTER ◽  
D. IMHOFF ◽  
M. KOCIAK ◽  
C. MORY ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Electron Energy ◽  
Transmission Electron Microscope ◽  
Electron Energy Loss Spectroscopy ◽  
Scanning Transmission Electron Microscope ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Energy Loss

The basics of electron energy loss spectroscopy (EELS) performed in the context of a scanning transmission electron microscope are described. This includes instrumentation, information contained in an EELS spectrum, data acquisition and processing, and some illustrations by a few examples.

SiO2 Formation at the Aluminum Oxide/Si(100) Interface

2002 ◽  
Vol 747 ◽  
Author(s):  
A. Roy Chowdhuri ◽  
C. G. Takoudis ◽  
R. F. Klie ◽  
N. D. Browning
Keyword(s):  
Electron Microscope ◽  
Aluminum Oxide ◽  
Energy Loss ◽  
Electron Energy ◽  
Transmission Electron Microscope ◽  
Scanning Transmission Electron Microscope ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Z Contrast ◽  
Electron Energy Loss

ABSTRACTThin films of aluminum oxide were deposited on clean Si(100) substrates using trimethylaluminum and oxygen at 300°C. Infrared spectroscopic and x-ray photoelectron spectroscopic analyses of these films showed no aluminum silicate or SiO2 phase formation at the film/substrate interface. The O/Al ratio in the as deposited film was found to be higher than that in stoichiometric Al2O3. On annealing the as deposited samples in Ar at higher temperatures, a peak due to the transverse optical phonon for the Si-O-Si stretching mode appeared in the infrared spectra. A combination of Z-contrast imaging and electron energy loss spectroscopy in the scanning transmission electron microscope confirmed that the annealed samples developed a layer of silicon dioxide at the aluminum oxide-Si interface. Z-contrast images and electron energy loss spectra, obtained while heating the sample inside the scanning transmission electron microscope were used to follow the interfacial SiO2 formation.

Performance of the Gatan PEELS™ on the VG HB501 STEM

1989 ◽  
Vol 47 ◽  
pp. 410-411
Author(s):  
Ondrej L. Krivanek ◽  
James H. Paterson ◽  
Helmut R. Poppa
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Beam Energy ◽  
Detection Efficiency ◽  
Beam Current ◽  
Scanning Transmission Electron Microscope ◽  
Parallel Detection ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Energy Loss

Parallel-detection electron energy-loss spectrometers offer several hundred times the detection efficiency of serial-detection spectrometers, as well as improved energy resolution. These advantages should be especially important when using a scanning transmission electron microscope (STEM) with a cold field emission gun (FEG), in which the available beam current is typically 10 to 100 times less than in a conventional TEM, while the beam energy spread is typically only 0.3 eV. We have therefore investigated the performance of the Gatan parallel-detection spectrometer (Gatan model 666 PEELS™) when mounted on the VG HB501 FEG STEM.

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