Design of a 400KV Ultrahigh-Resolution Analytical TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 134-135
Author(s):  
H. Tsuno ◽  
T. Honda ◽  
Y. Kokubo
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Spherical Aberration ◽  
New Technology ◽  
Objective Lens ◽  
Ultrahigh Resolution ◽  
X Ray ◽  
Analytical Tem ◽  
Analytical Electron ◽  
Analytical Electron Microscope

The condenser-objective (C/O) lens proposed by Riecke, which has a very short gap length and small spherical aberration, was utilized for a commercial 200 kV ultrahigh resolution analytical TEM by Yanaka and Kaneyama. Fig. 1 shows the relation between theoretical resolution and objective lens (OL) spherical aberration coefficient (Cs) at accelerating voltages 200-1250 kV. It was reported that the Cs of a 400kV high resolution TEM is 1.0 mm and its resolution is 0.167 nm. The Cs of 400kV analytical TEM is 1.8 mm and the pre-field spherical aberration coefficient (Csp) is 1.8 mm. Fig. 2 (A), (B) show beam broading in specimens against the thickness when a 200kV and a 400kV electron beam transmit the specimen (C-Au), respectively. The broading of 400kV electron beam is about half of 200kV one. Then it is expected that spacial resolution of x-ray analysis improve. The above-captioned 400kV ultrahigh resolution analytical TEM is designed by applying a new technology which is adopted for a 200kV ultrahigh resolution analytical electron microscope, JEM-2010.Its fundamental construction is the same as the 400kV analytical electron microscope JEM-4000FX, except the 0L. The goniometer is a modified JEM-2010 goniometer, because it is too small for 400kV EM. Although it was expected that the focus ampere turn increases because of its short gap length, the objective lens coil used by JEM-4000EX/FX is adopted, because it has enough capacity. The shapes of the upper yoke and objective polepiece were calculated by the finite element method (55×110 Meshes) under the following condition: (1) maximum tilting-angle 10° (2) x-ray take-off angle 17.5° and solid angle 0.068 strad (3) minimized Cs.

An Application of 200kV Ultrahigh Resolution Analytical Electron Microscope

1990 ◽  
Vol 48 (2) ◽  
pp. 98-99
Author(s):  
M. Suzuki ◽  
T. Kaneyama ◽  
E. Watanabe ◽  
M. Naruse ◽  
Y. Kokubo
Keyword(s):  
Electron Microscope ◽  
Spherical Aberration ◽  
Objective Lens ◽  
Theoretical Point ◽  
Ultrahigh Resolution ◽  
X Ray ◽  
Probe Current ◽  
Probe Size ◽  
Analytical Electron ◽  
Analytical Electron Microscope

A 200 kV ultrahigh resolution analytical electron microscope (UHRAEM), JEM-2010, enables both ultrahigh resolution imaging with a theoretical point resolution of 0.194 nm and nm-area analysis. In this paper, its preliminary data for x-ray analysis (Energy Dispersive X ray Spectroscopy: EDS) and its application data will be shown.An objective lens polepiece has been designed to minimize the spherical aberration coefficient (Cs) of the prefield and thereby increase the probe current in small probe size for nm-area EDS analysis. Measured values of Cs and chromatic aberration coefficient (Cc) are 0.5 mm and 1.0 mm, respectively. Fig. 1 shows a theoretical relation between the illumination angle and probe size of this objective lens on the assumption that the brightness of electrons is 6×106 A/cm2 • str in a LaB6 cathode. This calculation shows that an electron probe smaller than 1 nm in diameter is available even with a probe current of 10 pA.

Development of 200kV ultrahigh-resolution analytical electron microscope

1989 ◽  
Vol 47 ◽  
pp. 108-109
Author(s):  
T. Kaneyama ◽  
M. Naruse ◽  
Y. Ishida ◽  
M. Kersker
Keyword(s):  
Electron Microscope ◽  
Optical Constants ◽  
Materials Science ◽  
Objective Lens ◽  
The Finite Element Method ◽  
Ultrahigh Resolution ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Characteristic Features ◽  
Better Than

In the field of materials science, the importance of the ultrahigh resolution analytical electron microscope (UHRAEM) is increasing. A new UHRAEM which provides a resolution of better than 0.2 nm and allows analysis of a few nm areas has been developed. [Fig. 1 shows the external view] The followings are some characteristic features of the UHRAEM.Objective lens (OL)Two types of OL polepieces (URP for ±10' specimen tilt and ARP for ±30' tilt) have been developed. The optical constants shown in the table on the next page are figures calculated by the finite element method. However, Cs was experimentally confirmed by two methods (namely, Beam Tilt method and Krivanek method) as 0.45 ∼ 0.50 mm for URP and as 0.9 ∼ 1.0 mm for ARP, respectively. Fig. 2 shows an optical diffractogram obtained from a micrograph of amorphous carbon with URP under the Scherzer defocus condition. It demonstrates a resolution of 0.19 nm and a Cs smaller than 0.5 mm.

Development of high-performance objective lens polepiece for ultrahigh resolution Analytical Electron Microscope

1993 ◽  
Vol 51 ◽  
pp. 254-255
Author(s):  
K. Fukushima ◽  
T. Kaneyama ◽  
F. Hosokawa ◽  
H. Tsuno ◽  
T. Honda ◽  
...  
Keyword(s):  
Electron Microscope ◽  
High Performance ◽  
Open Space ◽  
Materials Science ◽  
Objective Lens ◽  
Ultrahigh Resolution ◽  
Science Field ◽  
Specimen Holder ◽  
Analytical Electron ◽  
Analytical Electron Microscope

Recently, in the materials science field, the ultrahigh resolution analytical electron microscope (UHRAEM) has become a very important instrument to study extremely fine areas of the specimen. The requirements related to the performance of the UHRAEM are becoming gradually severer. Some basic characteristic features required of an objective lens are as follows, and the practical performance of the UHRAEM should be judged by totally evaluating them.1) Ultrahigh resolution to resolve ultrafine structure by atomic-level observation.2) Nanometer probe analysis to analyse the constituent elements in nm-areas of the specimen.3) Better performance of x-ray detection for EDS analysis, that is, higher take-off angle and larger detection solid angle.4) Higher specimen tilting angle to adjust the specimen orientation.To attain these requirements simultaneously, the objective lens polepiece must have smaller spherical and chromatic aberration coefficients and must keep enough open space around the specimen holder in it.

Optimizing Spatial Resolution for X-ray Microanalysis

2001 ◽  
Vol 7 (S2) ◽  
pp. 694-695
Author(s):  
Eric Lifshin ◽  
Raynald Gauvin ◽  
Di Wu
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Spatial Resolution ◽  
Maximum Diameter ◽  
Thin Sections ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Limiting Value ◽  
Made In

In Castaing’s classic Ph.D. dissertation he described how the limiting value of x-ray spatial resolution for x-ray microanalysis, of about 1 μm, was not imposed by the diameter of the electron beam, but by the size of the region excited inside the specimen. Fifty years later this limit still applies to the majority of measurement made in EMAs and SEMs, even though there is often a need to analyze much finer structures. When high resolution chemical analysis is required, it is generally necessary to prepare thin sections and examine them in an analytical electron microscope where the maximum diameter of the excited volume may be as small as a few nanometers. Since it is not always possible or practical, it is important to determine just what is the best spatial resolution attainable for the examination of polished or “as received” samples with an EMA or SEM and how to achieve it experimentally.

Field Emission Analytical Electron Microscope

1976 ◽  
Vol 34 ◽  
pp. 528-529
Author(s):  
Y. Harada ◽  
Y. Kokubo ◽  
T. Goto ◽  
N. Tamura ◽  
M. Iwatsuki ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Objective Lens ◽  
General View ◽  
Energy Analyzer ◽  
X Ray ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Electron Microscopes

Recently, analytical electron microscopes (AEM), which provide the functions of the transmission electron microscope (TEM), scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS) have been put to practical use with a view to analyzing elements in micro areas, xo improve the performance of this type of AEM, a field emission gun was attached to our AEM instead of a conventional thermionic gun. This has allowed a sellected area smaller than several 100 Å to be easily analyzed. Moreover, an electron energy analyzer (EA) was attached to the AEM for detecting light elements which cannot be detected by the EDS.These modifications have resulted in an advanced type of an AEM, namely, a field emission analytical electron microscope (FEAEM).Fig. 1 shows a general view of our FEAEM. The feature of this FEAEM is that it is designed on the basis of a 100 kV field emission electron microscope provided with a strongly-excited objective lens having a very small aberration coefficient and with an eucentric goniometer tiltable to 60°.

High Resolution Side-Entry Goniometer

1980 ◽  
Vol 38 ◽  
pp. 56-57
Author(s):  
T. Honda ◽  
H. Watanabe ◽  
K. Ohi ◽  
E. Watanabe ◽  
Y. Kokubo
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Resolution Limit ◽  
Tilting Angle ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
High Resolution Images

An analytical electron microscope equipped with a side-entry goniometer (SEG) has recently become more widespread than a conventional electron microscope by the following reasons: (1) a variety of specimen holders, (2) large tilting angle with eucentricity. However, the resolution of SEG-system is about 0.4 nm, whereas the resolution of 0.25 nm or less can be obtained by an electron microscope equipped with a top-entry goniometer (TEG)1). Factors determining the resolution of an electron microscope are (1) the aberration coefficients of the objective lens, (2) stability of exciting currents, (3) illumination angle of the electron beam on the specimen, (4) energy spread of the electron beam, and ( 5) vibration and specimen drift. It has been usually difficult to observe high resolution images during use of the SEG system, because of the aberration coefficients of the objective lens, vibration and specimen drift. In order to obtain a resolution of less than 0.3 nm with SEG system at 200 kV, both of spherical and chromatic aberration coefficients should be reduced less than 2 mm. Moreover, relative amplitude of vibration between the specimen and pole pieces should be less than a half value of resolution limit. The image drift should be less than 0.02 nm/sec, because the exposure time usually required for photographing a high resolution image is about 5 second.

point-Analysis Using the Extrapolation Method in the Analytical Electron microscope

1990 ◽  
Vol 48 (2) ◽  
pp. 430-431
Author(s):  
Zenji Horita ◽  
Ryuzo Nishimachi ◽  
Takeshi Sano ◽  
Minoru Nemoto
Keyword(s):  
Electron Microscope ◽  
Extrapolation Method ◽  
X Ray ◽  
Absorption Correction ◽  
Point Analysis ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Data Points ◽  
Identical Composition ◽  
X Ray Absorption

Absorption correction is often required in quantitative x-ray microanalysis of thin specimens using the analytical electron microscope. For such correction, it is convenient to use the extrapolation method[l] because the thickness, density and mass absorption coefficient are not necessary in the method. The characteristic x-ray intensities measured for the analysis are only requirement for the absorption correction. However, to achieve extrapolation, it is imperative to obtain data points more than two at different thicknesses in the identical composition. Thus, the method encounters difficulty in analyzing a region equivalent to beam size or the specimen with uniform thickness. The purpose of this study is to modify the method so that extrapolation becomes feasible in such limited conditions. Applicability of the new form is examined by using a standard sample and then it is applied to quantification of phases in a Ni-Al-W ternary alloy.The earlier equation for the extrapolation method was formulated based on the facts that the magnitude of x-ray absorption increases with increasing thickness and that the intensity of a characteristic x-ray exhibiting negligible absorption in the specimen is used as a measure of thickness.

Peak-to-background measurements on a 300-kV TEM/STEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1236-1237 ◽  
Author(s):  
S. M. Zemyan ◽  
D. B. Williams
Keyword(s):  
Electron Microscope ◽  
X Ray ◽  
Background Ratio ◽  
Window Method ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Cr Film

As has been reported elsewhere, a thin evaporated Cr film can be used to monitor the x-ray peak to background ratio (P/B) in an analytical electron microscope. Presented here are the results of P/B measurements for the Cr Ka line on a Philips EM430 TEM/STEM, with Link Si(Li) and intrinsic Ge (IG) x-ray detectors. The goal of the study was to determine the best conditions for x-ray microanalysis.We used the Fiori P/B definition, in which P/B is the ratio of the total peak integral to the average background in a 10 eV channel beneath the peak. Peak and background integrals were determined by the window method, using a peak window from 5.0 to 5.7 keV about Cr Kα, and background windows from 4.1 to 4.8 keV and 6.3 to 7.0 keV.

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