Methods to quantify silver in autoradiographs

1980 ◽  
Vol 238 (3) ◽  
pp. H414-H422
Author(s):  
D. L. Fry ◽  
A. J. Tousimis ◽  
T. L. Talbot ◽  
S. J. Lewis
Keyword(s):  
Electron Beam ◽  
Current Density ◽  
Electron Probe ◽  
Beam Current ◽  
Silver Concentration ◽  
Electron Beam Current ◽  
Beam Size ◽  
X Ray ◽  
Small Variance ◽  
Arterial Tissue

The developed silver in specially prepared photographic films (PF) and autoradiographs (AR) of radiolabeled arterial tissue was quantified by direct grain counting (GC), microdensitometry (OD), and by electron probe X-ray microanalysis (EPA). The EPA data was proportional to the OD data with a very small variance. The GC data increased with the EPA data, but showed a large variance. The EPA signal was shown 1) to be reproducible even after multiple traverses across the specimen, 2) to be directly proportional to the electron beam current and emulsion silver concentration, and 3) to be insensitive to a) beam size, b) current density, c) energy above 17 keV, or d) nonuniformities in the thickness of the conductive coating on the specimen.

scholarly journals Time behavior of an electron beam current pulse in the axial and peripheral zones of an anode in vacuum and gas-filled diodes

2021 ◽  
Vol 2064 (1) ◽  
pp. 012031
Author(s):  
D A Sorokin ◽  
M I Lomaev ◽  
A V Dyatlov ◽  
V F Tarasenko
Keyword(s):  
Electron Beam ◽  
Current Pulse ◽  
Current Density ◽  
Beam Current ◽  
Beam Current Density ◽  
Electron Beam Current ◽  
Time Behavior ◽  
Beam Current Pulse ◽  
Axial Part ◽  
A Current

Abstract The study of the time behavior of a current pulse of an electron beam generated during a high-voltage nanosecond discharge in gas-filled and vacuum diodes has been carried out. As follows from the experimental results, in both cases, the distribution of the beam current density in the plane of a grounded anode is non-uniform. The highest beam current density is recorded in the axial part of the anode. It was established that in the case of a gas-filled diode, ~ 2 ns after the onset of the beam current pulse, its shape in the axial anode zone changes relative to that in the peripheral one. It is assumed that the most probable reason for this is the effect of compensation of the charge of the beam electrons by the positive charge of ions arising in the ionization process in the paraxial zone.

The output window of a large-area accelerator with an increased electron-beam current density

2017 ◽  
Vol 60 (4) ◽  
pp. 570-574
Author(s):  
G. A. Baranov ◽  
V. A. Gurashvili ◽  
I. D. Djigailo ◽  
N. I. Kazachenko ◽  
S. L. Kosogorov ◽  
...  
Keyword(s):  
Electron Beam ◽  
Current Density ◽  
Beam Current ◽  
Beam Current Density ◽  
Electron Beam Current ◽  
Large Area ◽  
Output Window

Characterization of a Fixed Beam Electron Microscope with a Field Emission Gun

1976 ◽  
Vol 34 ◽  
pp. 526-527
Author(s):  
Wah Chiu ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Current Density ◽  
Beam Current ◽  
Beam Current Density ◽  
Objective Lens ◽  
Electron Beam Current ◽  
Beam Electron ◽  
Fixed Beam

One of the objectives of our research program is to obtain a 2.0 Å point to point resolution in a fixed beam bright field electron microscope. The resolution in the fixed beam electron microscope is limited by a number of factors: electron beam coherence, energy spread, objective lens stability, mechanical stability, and specimen stability. This paper presents systematic studies of the mentioned factors in our JEM 100B fixed beam electron microscope equipped with a field emission gun operating at ∼ 1800°K.The most important characteristic of a field emission gun is its high brightness in the emitter source. In order to estimate the brightness at the specimen plane, one needs to measure the electron beam current density and the angle of illumination. The electron beam current density has been measured by means of a lithium-drifted silicon detector located below the normal position of the photographic plates. The angle of illumination can be estimated from the size of the condenser aperture and its distance from the specimen plane.

An Analytical Method of Time Character of Electron Beam Current Density on Transmission Electron Microscope Imaging

2013 ◽  
Vol 694-697 ◽  
pp. 1372-1376
Author(s):  
Xiu Yan Zhang ◽  
Quan Lin Dong
Keyword(s):  
Electron Beam ◽  
Exposure Time ◽  
Current Density ◽  
Analytical Method ◽  
Least Squares Method ◽  
Beam Current ◽  
Test Equipment ◽  
Beam Current Density ◽  
Electron Beam Current ◽  
Transmission Electron

An analytical method of time character of electron beam current density is required for transmission electron microscopy (TEM) imaging research. By studying the imaging principle of TEM, the relational expression between current density on fluorescent screen and exposure time is deduced. The actual data of numerical relation between current density and exposure time are gained by the exposure experimentation with the master sample on the TEM test equipment. Furthermore, the parameter value in expression is computed by linear fit using the least squares method, and then the concrete relational expression between current density and exposure time about the TEM test equipment is obtained. As a result, using the concrete relational expression on the TEM test equipment, the automatic exposure experimentation on some samples is completed on the different operating mode, and the relatively clear-cut TEM images are formed. The experimentation results indicate that the automatic exposure method is correct and parameter calibration is valid.

Elemental mass loss in silicate minerals during x-ray analysis

1990 ◽  
Vol 48 (4) ◽  
pp. 804-805
Author(s):  
P.E. Champness ◽  
R.W. Devenish
Keyword(s):  
Mass Loss ◽  
Current Density ◽  
Damage Mechanism ◽  
Beam Current ◽  
Single Chain ◽  
Plagioclase Feldspar ◽  
X Ray ◽  
Alkali Ions ◽  
Structural Order ◽  
Sheet Silicate

It has long been recognised that silicates can suffer extensive beam damage in electron-beam instruments. The predominant damage mechanism is radiolysis. For instance, damage in quartz, SiO2, results in loss of structural order without mass loss whereas feldspars (framework silicates containing Ca, Na, K) suffer loss of structural order with accompanying mass loss. In the latter case, the alkali ions, particularly Na, are found to migrate away from the area of the beam. The aim of the present study was to investigate the loss of various elements from the common silicate structures during electron irradiation at 100 kV over a range of current densities of 104 - 109 A m−2. (The current density is defined in terms of 50% of total current in the FWHM probe). The silicates so far ivestigated are:- olivine [(Mg, Fe)SiO4], a structure that has isolated Si-O tetrahedra, garnet [(Mg, Ca, Fe)3Al2Si3AO12 another silicate with isolated tetrahedra, pyroxene [-Ca(Mg, Fe)Si2O6 a single-chain silicate; mica [margarite, -Ca2Al4Si4Al4O2O(OH)4], a sheet silicate, and plagioclase feldspar [-NaCaAl3Si5O16]. Ion- thinned samples of each mineral were examined in a VG Microscopes UHV HB501 field- emission STEM. The beam current used was typically - 0.5 nA and the current density was varied by defocussing the electron probe. Energy-dispersive X-ray spectra were collected every 10 seconds for a total of 200 seconds using a Link Systems windowless detector. The thickness of the samples in the area of analysis was normally 50-150 nm.

Sign in / Sign up

Export Citation Format

Share Document