Synthesis, Analysis, Transport and Field emission Measurements of Compound B-C-N Nanotubes

2003 ◽  
Vol 772 ◽  
Author(s):  
Dmitri Golberg ◽  
Yoshio Bando ◽  
Pavel Dorozhkin ◽  
Zhen-Chao Dong ◽  
Cheng-Chun Tang ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Chemical Compositions ◽  
Scanning Tunnelling Microscope ◽  
Field Emission Properties ◽  
Transmission Electron ◽  
Scanning Tunnelling ◽  
Low Energy Electron ◽  
Electron Energy Loss

AbstractMultiwalled B-C-N nanotubes of various morphologies and chemical compositions were synthesized by reacting C-based nanotube templates with boron oxide and nitrogen at 1573 K- 2173 K. The nanotubes were thoroughly analysed using a high-resolution field-emission 300 kV transmission electron microscope (TEM), an energy-filtered field-emission 300 kV electron microscope (Omega filter), an electron energy loss spectrometer and an energy dispersion X-ray detector. Transport and field emission properties of the nanotubes were studied using a low energy electron point source microscope and via in-situ measurements in TEM equipped with a scanning tunnelling microscope (STM) unit.

2. Studying minerals

2014 ◽  
Author(s):  
David Vaughan
Keyword(s):  
Electron Microscope ◽  
Chemical Compositions ◽  
Scanning Tunnelling Microscope ◽  
X Ray Crystallography ◽  
Atomic Force ◽  
Transmission Electron ◽  
Reflected Light ◽  
Scanning Tunnelling ◽  
Electron Microscopes ◽  
Surface Chemistries

The study of minerals begins with their characterization, identification, and classification determined from their chemical compositions and crystallographic properties. ‘Studying minerals’ shows that historically this was based on properties observable in hand specimens, but the development of wide-ranging techniques has allowed the study of all aspects of minerals: their structures, chemistries, surface chemistries, and reactivities. Techniques described include transmitted light and reflected light microscopy using thin and polished sections; X-ray crystallography based on Bragg’s Law; techniques using various forms of electromagnetic radiation; and electron microscopes including the transmission electron microscope, scanning electron microscope, scanning tunnelling microscope, and atomic force microscope.

An improved design for an Scanning Tunnelling Microscope (STM) for use in a Transmission Electron Microscope (TEM)

1991 ◽  
Vol 49 ◽  
pp. 384-385
Author(s):  
W.K. Lo ◽  
J.C.H. Spence
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Mechanical Stability ◽  
Scanning Tunnelling Microscope ◽  
Reflection Mode ◽  
Specimen Holder ◽  
Transmission Electron ◽  
Scanning Tunnelling ◽  
Improved Design

An improved design for a combination Scanning Tunnelling Microscope/TEM specimen holder is presented. It is based on earlier versions which have been used to test the usefulness of such a device. As with the earlier versions, this holder is meant to replace the standard double-tilt specimen holder of an unmodified Philips 400T TEM. It allows the sample to be imaged simultaneously by both the STM and the TEM when the TEM is operated in the reflection mode (see figure 1).The resolution of a STM is determined by its tip radii as well as its stability. This places strict limitations on the mechanical stability of the tip with respect to the sample. In this STM the piezoelectric tube scanner is rigidly mounted inside the endcap of the STM holder. The tip coarse approach to the sample (z-direction) is provided by an Inchworm which is located outside the TEM vacuum.

Surface study by UHV electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 458-459
Author(s):  
K. Yagi ◽  
K. Takayanagi ◽  
K. Kobayashi ◽  
N. Osakabe ◽  
Y. Tanishiro ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Film Growth ◽  
Atomic Layer ◽  
Chemical Compositions ◽  
Surface Phenomena ◽  
Transmission Electron ◽  
In Situ Deposition ◽  
Complementary Role ◽  
Atomically Flat

Recent advances of UHV techniques, LEED, RHEED and AES, arose a surge of interest on the surface of solids. These techniques reveal structures and chemical compositions at the mono-atomic or mono-molecular level. All of them, however, are devoid of detailed topographic informations, although some efforts to introduce the scanning techniques have been done[l]. Transmission electron microscopy of high resolution should play a complementary role to these techniques. No attempt, however, has been done previously to use it to such a purpose. This was because it was difficult to get and keep clean surfaces in the poor vacuum at 1x10-5 Torr level of the conventional electron microscope.The present paper reports observations of surface phenomena of one or two atomic layer level using a UHV JEM 100B electron microscope (10-8 -10-10Torr), recently developed for insitu thin film growth studies[2]. Atomically flat (111) surfaces of Ag, Pd, Au and Cu were prepared by in- situ deposition at 150-350°C on M0S2, graphite and MgO. Air Cleaved thin films of MoS2 and graphite were preheated to 800°C to get clean surfaces[3].

Analysis of Cellular Organelles and Macromolecular Assemblies by Electron Energy Loss Spectroscopy

1996 ◽  
Vol 54 ◽  
pp. 290-291
Author(s):  
R.D. Leapman ◽  
S.B. Andrews
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Energy Loss ◽  
Field Emission ◽  
Transmission Electron Microscope ◽  
Electron Energy Loss Spectroscopy ◽  
Low Loss ◽  
Macromolecular Assemblies ◽  
Transmission Electron ◽  
Electron Energy Loss

Recent advances in electron energy loss spectroscopy (EELS) have significantly extended the range of applications for biological microanalysis. For example, EELS can now detect physiological concentrations of the important element calcium in rapidly frozen cells with a sensitivity greater than that achievable by energy-dispersive x-ray spectroscopy (EDXS). It can also detect small numbers of phosphorus atoms bound to macromolecular assemblies, and measure water distributions in frozen hydrated tissue. Here we discuss some of these developments in the context of detection limits and mapping techniques in the scanning transmission electron microscope (STEM) and energy-filtering transmission electron microscope (EFTEM).The useful information about elemental composition in EELS of biological specimens generally resides in weak core-edge signals corresponding to atomic concentrations in the 10−5−10−3 (1–100 mmol/kg dry weight) range. For example, the Ca L2,3 signal/background ratio is typically only 10−3 and it is necessary to measure differences in signal that are only 104 of the background. Changes in low-loss fine structure corresponding to varying chemical composition are also very subtle; for example, detection of a 3% change in water content requires reliable measurement of a 0.1 eV shift in the low-loss intensity maximum. To extract such information requires efficient parallel detection of the energy loss spectrum and a high-brightness source to provide a sufficient number of incident electrons. The dedicated STEM is particularly well-suited for analyzing low concentrations of biological elements. If desired, the probe current can be reduced into the picoampere range for low-dose, high-resolution imaging prior to elemental analysis. The STEM’S field-emission source can then be used to deliver a current approaching 10 nA into a ~10 nm diameter probe. High electron flux conditions are ideal for spectrum-imaging applications where adequate counting statistics must be achieved within a limited pixel dwell time. The cold field-emission source of the STEM has the additional advantage of providing electrons with a narrow energy spread of <0.5 eV which is important in fine structure studies.

An Analytical Scanning Transmission Electron Microscope

1975 ◽  
Vol 33 ◽  
pp. 130-131
Author(s):  
H. von Harrach ◽  
C.E. Lyman ◽  
A.R. Walker ◽  
D.C. Joy ◽  
G.R. Booker
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Transmission Electron Microscope ◽  
Scanning Transmission Electron Microscope ◽  
Loss Analysis ◽  
Scanning Transmission Electron ◽  
Quantitative Microanalysis ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Energy Loss

A scanning transmission electron microscope (STEM) with a field emission gun has been developed for quantitative microanalysis. The high brightness source combined with X-ray analysis, electron diffraction and electron energy loss analysis provides a technique of microanalysis from regions of thin specimens as small as a few hundred angstroms.The electron optical lay-out of this microscope is shown in Figure 1. A triode field-emission gun is mounted in a U HV chamber with mu-metal walls for screening. The gun which can be operated at up to 100kV provides a virtual source; the position of this source is largely independent of the ratio of the acceleration voltage to extraction voltage.

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