scholarly journals Sub-Ångstrom Resolution

2003 ◽  
Vol 11 (6) ◽  
pp. 3-7
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Electron Microscope ◽  
Light Microscope ◽  
High Energy ◽  
Scanning Transmission Electron Microscope ◽  
Significant Advance ◽  
Contrast Method ◽  
Transmission Electron ◽  
High Energy Electrons ◽  
Scanning Transmission ◽  
Z Contrast

Antoni van Leeuwenhoek showed the practical use of the light microscope in the 1600s after much effort to improve the quality of optical lenses. Pioneering microscopists such as Ernst Abbé, Hermann Ludwig Ferdinand von Helmholtz, Lord John Rayleigh, Carl Zeiss, and August Köhler then brought us to the brink of optimal performance of the light microscope approximately a century ago, Ernst Ruska and Max Knoll showed in the 1930s that high-energy electrons could be used in place of light, giving greatly improved resolution. In the 1970's Albert Crewe and co-workers developed the scanning transmission electron microscope (STEM) and used the Z-contrast method to improve resolution in the electron microscope by about a factor of two. The scanning probe (nonoptical) microscopes aside, there hasn't been a significant advance in spatial resolution since.

Energy-Filtered CTEM Image of MgO Smoke Particles

1985 ◽  
Vol 43 ◽  
pp. 410-411
Author(s):  
Y. Kondo ◽  
T. Yoshioka ◽  
T. Oikawa ◽  
Y. Kokubo ◽  
M. Kersker
Keyword(s):  
Electron Microscope ◽  
Energy Resolution ◽  
Transmission Electron Microscope ◽  
High Energy ◽  
Scanning Transmission Electron Microscope ◽  
High Energy Resolution ◽  
Energy Analyzer ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Sector Type

The energy filtered imaging technique has so far been carried out in a scanning transmission electron microscope (STEM) fitted with a sector type energy analyzer. The STEM has a disadvantage of low beam parallelity because it uses a convergent beam, while the conventional transmission electron microscope (CTEM) allows good phase contrast and diffraction contrast to be obtained because of the high parallelity of the beam, and allows also high resolution images to be obtained. The technique to obtain energy filtered CTEM images has thus far been carried out by a Castaing-Henry type filter or an Ω type filter. However, these filters have the disadvantage of lower energy resolution than conventional sector type energy analyzer at the present time. This paper reports energy filtered CTEM images of MgO smoke, obtained using a new scanning CTEM image technique and a high energy resolution sector type energy analyzer which can resolve bulk and surface plasmon energy.

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.

A Novel Diode Detector in a Scanning Transmission Microscope

1972 ◽  
Vol 30 ◽  
pp. 442-443
Author(s):  
C. S. Kim ◽  
T. E. Everhart
Keyword(s):  
High Energy ◽  
Scanning Transmission Electron Microscope ◽  
Semiconductor Diode ◽  
Objective Lens ◽  
Contrast Effects ◽  
Thin Sample ◽  
Transmission Electron ◽  
High Energy Electrons ◽  
Scanning Transmission ◽  
Pass Through

High-resolution in a scanning transmission electron microscope can be obtained using a condenser-objective lens. A suitable semiconductor diode is an efficient detector of high-energy electrons; an annular detector allows unscattered primary electrons or inelastically scattered electrons to pass through the hole, while elastically scattered electrons strike the diode, and are detected.Electrons passing through a thin sample may be elastically scattered through angles of many tens of milliradians, inelastically scattered with angular deflections of ∼ 1 mr, or not scattered at all. The inelastically scattered electrons do not depart significantly from the unscattered beam. Since the beam convergence angle at the sample is typically a few milliradians, the elastically scattered electrons can be collected using a detector with a hole positioned at the beam axis to allow the inelastically scattered electrons and the unscattered electrons to pass through. These electrons can be separated with an electron spectrometer to provide important contrast effects.

Comparison of Scanning Transmission and Backscattered Electron Imaging in the Sem, Using Heavy Metal Stained Sections of Biological Tissue

1976 ◽  
Vol 34 ◽  
pp. 322-323
Author(s):  
Phillip B. DeNee ◽  
Richard G. Frederickson
Keyword(s):  
Heavy Metal ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Light Microscope ◽  
Biological Tissues ◽  
Scanning Transmission Electron Microscope ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Backscattered Electron ◽  
Better Than

The Transmission Electron Microscope (TEM) has been used extensively for the study of biological tissues in thin section (50-100 nm). For sectioned material greater than 100 nm, the Scanning Transmission Electron Microscope (STEM) and the High Voltage Electron Microscope (HVEM) have become the only alternatives for the study of these tissues at a resolution better than that obtained with the light microscope. Recently, it has been shown(1) that tissue stained with heavy metal can be studied in the Scanning Electron Microscope (SEM) by Backscattered Electron (BSE) imaging to give results similar to those obtained with the TEM. Because BSE imaging is a method complementary to STEM, it seemed worthwhile to compare the two techniques using the same specimens and beam conditions.Direct observation of the total specimen is possible with BSE imaging without interference by grid bars. Therefore, an improved perspective of tissue-totissue structural relationships can be obtained at a resolution significantly better than that of the light microscope.

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