A Wien Filter Electron Energy Loss Spectrometer for Transmission Electron Microscopy

1990 ◽  
Vol 48 (2) ◽  
pp. 32-33
Author(s):  
K. Tsuno ◽  
J. Ohyama ◽  
M. Kato ◽  
J. Kimura ◽  
M. Kai ◽  
...  
Keyword(s):  
Imaging System ◽  
Optical Axis ◽  
Detection System ◽  
High Energy ◽  
High Energy Resolution ◽  
Wien Filter ◽  
Magnetic Forces ◽  
Transmission Electron ◽  
Electron Energy Loss ◽  
Post Filter

A retarding Wien filter has been installed in the transmission electron microscope (TEM) JEM-1200EX. The filter is immersed in a high potential (-Ht + Uo ) nearly equal to the accelerating potential (-Ht) to get high energy resolution. The Wien filter consists of crossed electric (E) and magnetic (B) fields perpendicular to the optical axis. Electrons with a particular velocity v have a straight optical axis if the balancing condition between electric and magnetic forces (Wien condition: E=vB) is satisfied. Electrons with different velocity are deflected.Fig. 1 shows a schematic outline of the present instrument. It consists of (1) TEM, (2) an analyzer made of the Wien filter, deflectors and post filter lenses, and (3) a TV camera imaging system and serial detection system. The analyzer and a serial detection system are controlled by a personal computer PC-9801VX (PC). Table 1 shows currents and voltages of the filter, lenses and deflectors (upper) and those for TEM (lower).

Investigation of low-loss spectra and near-edge fine structure of polymers by peels

1996 ◽  
Vol 54 ◽  
pp. 158-159
Author(s):  
W. Heckmann
Keyword(s):  
Electron Microscopy ◽  
High Sensitivity ◽  
High Energy ◽  
High Energy Resolution ◽  
Imaging Method ◽  
Low Loss ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Electron Energy Loss ◽  
Loss Range

Transmission electron microscopy has changed from a purely imaging method to an analytical method. This has been facilitated particularly by equipping electron microscopes with energy filters and with parallel electron energy loss spectrometers (PEELS). Because of their relatively high energy resolution (1 to 2 eV) they provide information not only on the elements present but also on the type of bonds between the molecular groups. Polymers are radiation sensitive and the molecular bonds change as the spectrum is being recorded. This can be observed with PEEL spectrometers that are able to record spectra with high sensitivity and in rapid succession.A PEEL spectrum can be divided into a low loss range and an inner shell loss range of higher energy. The low loss spectra of polymers always show a broad peak at about 22 eV and a further peak at 7 eV, if aromatic groups are present, as is the case with PS (Fig. 1). In the course of exposure, the intensity of this peak decreases, a sign that the benzene ring is destroyed by the radiation (Fig. 2).

High-energy-resolution monochromator for aberration-corrected scanning transmission electron microscopy/electron energy-loss spectroscopy

2009 ◽  
Vol 367 (1903) ◽  
pp. 3683-3697 ◽  
Author(s):  
Ondrej L. Krivanek ◽  
Jonathan P. Ursin ◽  
Neil J. Bacon ◽  
George J. Corbin ◽  
Niklas Dellby ◽  
...  
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Electron Energy Loss Spectroscopy ◽  
High Energy ◽  
High Energy Resolution ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Energy Loss

An all-magnetic monochromator/spectrometer system for sub-30 meV energy-resolution electron energy-loss spectroscopy in the scanning transmission electron microscope is described. It will link the energy being selected by the monochromator to the energy being analysed by the spectrometer, without resorting to decelerating the electron beam. This will allow it to attain spectral energy stability comparable to systems using monochromators and spectrometers that are raised to near the high voltage of the instrument. It will also be able to correct the chromatic aberration of the probe-forming column. It should be able to provide variable energy resolution down to approximately 10 meV and spatial resolution less than 1 Å.

A new high-resolution Electron Energy-Loss Spectroscopy microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 940-941
Author(s):  
Michiyoshi Tanaka ◽  
Masami Terauchi ◽  
Ryuichi Kuzuo ◽  
Katsushige Tsuno ◽  
Junichi Ohyama ◽  
...  
Keyword(s):  
High Resolution ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
High Energy ◽  
High Energy Resolution ◽  
Basic Part ◽  
Wien Filter ◽  
Resolution Electron ◽  
Electron Energy Loss

Boersch, Geiger and coworkers constructed high resolution electron energy-loss spectroscopy (EELS) instruments. These had a very high energy resolution of approximately 3meV, but were operated at a relatively low accelerating voltage of about 30kV and could only obtain spectra from specimen areas greater than about 10µm in diameter.We have been developing a new EELS instrument to investigate detailed electronic structures and thermal vibrations by taking spectra from specified small specimen areas and specified small reciprocal space areas. Our EELS microscope is composed of a thermal-type field emission gun, a Wien-filter monochrometer, the basic part of a JEM-1200EX microscope, a Wien-filter analyzer and a CCD detection system (Fig.1). Figure 2 schematically shows an xy-section of the Wien filter. The filter was designed to produce the Wien condition E=vxB (E:electric field, B:magnetic field, v:velocity of electrons) not only in the filter but also in the fringing field regions and to produce the stigmatic focus. The length of the filter was chosen to be 4cm.

First Applications of Electron Energy-Loss Spectroscopy with High Energy Resolution

2002 ◽  
Vol 738 ◽  
Author(s):  
Gerald Kothleitner ◽  
Christoph Mitterbauer ◽  
Werner Grogger ◽  
Henny Zandbergen ◽  
Peter Tiemeijer ◽  
...  
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Chemical Bonding ◽  
High Energy ◽  
Structural Features ◽  
High Energy Resolution ◽  
Transmission Electron ◽  
New Instrument ◽  
Electron Energy Loss

ABSTRACTA new transmission electron microscope equipped with a monochromator and a high resolution energy-filter was used for the first time to fully exploit the chemical bonding information contained in the near edge fine structures (ELNES) of electron energy-loss spectra. The instrument is capable of acquiring spectra with an energy resolution in the range of 0.1 eV, thus opening up the way for improved ELNES information. ELNES spectra of TiO2 and CoO have been recorded and are compared with data obtained with a conventional microscope and with x-ray absorption spectroscopy. In case of the L2,3 edges of the transition metals the new instrument revealed previously unobservable fine structure details, but for the O K edges the improved energy resolution does not result in more detailed structural features than observable in common microscopes. Furthermore, the potential of the new microscope to obtain chemical bonding information at the nanometer scale is discussed.

scholarly journals Reliable Characterization of Organic & Pharmaceutical Compounds with High Resolution Monochromated EEL Spectroscopy

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1434
Author(s):  
Partha Pratim Das ◽  
Giulio Guzzinati ◽  
Catalina Coll ◽  
Alejandro Gomez Perez ◽  
Stavros Nicolopoulos ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Drug Product ◽  
Amorphous Solid ◽  
High Energy ◽  
New Drugs ◽  
High Energy Resolution ◽  
Amorphous Solid Dispersion ◽  
Pharmaceutical Ingredients ◽  
Transmission Electron ◽  
Optical Region

Organic and biological compounds (especially those related to the pharmaceutical industry) have always been of great interest for researchers due to their importance for the development of new drugs to diagnose, cure, treat or prevent disease. As many new API (active pharmaceutical ingredients) and their polymorphs are in nanocrystalline or in amorphous form blended with amorphous polymeric matrix (known as amorphous solid dispersion—ASD), their structural identification and characterization at nm scale with conventional X-Ray/Raman/IR techniques becomes difficult. During any API synthesis/production or in the formulated drug product, impurities must be identified and characterized. Electron energy loss spectroscopy (EELS) at high energy resolution by transmission electron microscope (TEM) is expected to be a promising technique to screen and identify the different (organic) compounds used in a typical pharmaceutical or biological system and to detect any impurities present, if any, during the synthesis or formulation process. In this work, we propose the use of monochromated TEM-EELS, to analyze selected peptides and organic compounds and their polymorphs. In order to validate EELS for fingerprinting (in low loss/optical region) and by further correlation with advanced DFT, simulations were utilized.

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