Electron Transmission Measurements for Al, Sn, and Au Targets at Electron Bombarding Energies of 1.0 and 2.5 MeV

The intensity of characteristic x-rays /IiX/ from thin self-supporting samples depends not only on the concentration /c/ of the excited element but also on the mass thickness /ƍD/ of the film:The ki factors can be determined on thin etalon films of known thickness. So as to carry out quantitative analysis of thin samples, it is necessary to measure the local ƍ D independently of the measurement of x-ray intensities.In this paper a method is described to determine the mass thickness of thin samples by electron transmission and their chemical composition by combining the x-ray intensity and electron transmission measurements.It is known that some polycrystalline films e.g. Au, Ag, Sb, Bi and Cu films, exhibit anomalous behaviour in the exponential dependence of electron transmission on ƍD. Therefore we have developed a method for the measurement of electron transmission which overcomes the influence of Bragg reflection electrons.

Download Full-text

Low energy electron transmission measurements on polydiacetylene Langmuir-Blodgett films

Thin Solid Films ◽

10.1016/0040-6090(89)90203-4 ◽

1989 ◽

Vol 179 (1-2) ◽

pp. 327-334 ◽

Cited By ~ 8

Author(s):

Toshiteru Maeda ◽

Kenjiro Miyano ◽

Kazuyuki Sugita ◽

Nobuo Ueno

Keyword(s):

Low Energy ◽

Energy Electron ◽

Langmuir Blodgett ◽

Electron Transmission ◽

Langmuir Blodgett Films ◽

Low Energy Electron ◽

Transmission Measurements

Download Full-text

Ultrastructure of Melanin Formation in Curvularia sp., Alternaria sp., and Drechslera Sorokiniana

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079449 ◽

1977 ◽

Vol 35 ◽

pp. 398-399

Author(s):

M. H. Wheeler ◽

W. J. Tolmsoff ◽

A. A. Bell

Keyword(s):

Potassium Phosphate ◽

Thielaviopsis Basicola ◽

Wild Type ◽

Potassium Phosphate Buffer ◽

Transmission Microscopy ◽

Electron Transmission ◽

Melanin Formation ◽

Before And After ◽

Alternaria Sp ◽

Electron Transmission Microscopy

(+)-Scytalone [3,4-dihydro-3,6,8-trihydroxy-l-(2Hj-naphthalenone] and 1,8-di- hydroxynaphthalene (DHN) have been proposed as intermediates of melanin synthesis in the fungi Verticillium dahliae (1, 2, 3, 4) and Thielaviopsis basicola (4, 5). Scytalone is enzymatically dehydrated by V. dahliae to 1,3,8-trihydroxynaphthalene which is then reduced to (-)-vermelone [(-)-3,4- dihydro-3,8-dihydroxy-1(2H)-naphthalenone]. Vermelone is subsequently dehydrated to DHN which is enzymatically polymerized to melanin.Melanin formation in Curvularia sp., Alternaria sp., and Drechslera soro- kiniana was examined by light and electron-transmission microscopy. Wild-type isolates of each fungus were compared with albino mutants before and after treatment with 1 mM scytalone or 0.1 mM DHN in 50 mM potassium phosphate buffer, pH 7.0. Both chemicals were converted to dark pigments in the walls of hyphae and conidia of the albino mutants. The darkened cells were similar in appearance to corresponding cells of the wild types under the light microscope.

Download Full-text

Electrolytic Isolation of Twin-Type Shock Deformation Structures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100061604 ◽

1967 ◽

Vol 25 ◽

pp. 318-319

Author(s):

F. I. Grace ◽

L. E. Murr

Keyword(s):

Grain Boundaries ◽

Thin Foil ◽

Electrolyte Composition ◽

Experimental Conditions ◽

Average Current Density ◽

Electron Transmission ◽

Deformation Structures ◽

The Matrix ◽

Average Current ◽

Specimen Edge

During the course of electron transmission investigations of the deformation structures associated with shock-loaded thin foil specimens of 70/30 brass, it was observed that in a number of instances preferential etching occurred along grain boundaries; and that the degree of etching appeared to depend upon the various experimental conditions prevailing during electropolishing. These included the electrolyte composition, the average current density, and the temperature in the vicinity of the specimen. In the specific case of 70/30 brass shock-loaded at pressures in the range 200-400 kilobars, the predominant mode of deformation was observed to be twin-type faults which in several cases exhibited preferential etching similar to that observed along grain boundaries. A novel feature of this particular phenomenon was that in certain cases, especially for twins located in the vicinity of the specimen edge, the etching or preferential electropolishing literally isolated these structures from the matrix.

Download Full-text

A Stationary Solution of High-Energy Electron Reflection (HEER) for An Arbitrary Surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100135472 ◽

1990 ◽

Vol 48 (2) ◽

pp. 374-375

Author(s):

YIQUN MA

Keyword(s):

Stationary Solution ◽

High Energy ◽

Bloch Wave ◽

Dynamical Theory ◽

High Energy Electron ◽

Bulk Materials ◽

Periodic Surface ◽

Electron Transmission ◽

Electron Reflection ◽

Long Time

For a long time, the development of dynamical theory for HEER has been stagnated for several reasons. Although the Bloch wave method is powerful for the understanding of physical insights of electron diffraction, particularly electron transmission diffraction, it is not readily available for the simulation of various surface imperfection in electron reflection diffraction since it is basically a method for bulk materials and perfect surface. When the multislice method due to Cowley & Moodie is used for electron reflection, the “edge effects” stand firmly in the way of reaching a stationary solution for HEER. The multislice method due to Maksym & Beeby is valid only for an 2-D periodic surface.Now, a method for solving stationary solution of HEER for an arbitrary surface is available, which is called the Edge Patching method in Multislice-Only mode (the EPMO method). The analytical basis for this method can be attributed to two important characters of HEER: 1) 2-D dependence of the wave fields and 2) the Picard iteractionlike character of multislice calculation due to Cowley and Moodie in the Bragg case.

Download Full-text

Sound Transmission Measurements at 8 and 16 KC in Caribbean Waters, Spring, 1949,

10.21236/adc061977 ◽

1949 ◽

Author(s):

R. J. Urick

Keyword(s):

Sound Transmission ◽

Transmission Measurements

Download Full-text

Terahertz characterization of two-dimensional low-conductive layers enabled by metal gratings

Scientific Reports ◽

10.1038/s41598-021-82560-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Prashanth Gopalan ◽

Yunshan Wang ◽

Berardi Sensale-Rodriguez

Keyword(s):

Optical Transmission ◽

Terahertz Spectroscopy ◽

Design Guidelines ◽

Two Dimensional ◽

Highly Sensitive ◽

Transmission Measurements ◽

Metal Gratings ◽

Low Sensitivity ◽

Non Destructive

AbstractWhile terahertz spectroscopy can provide valuable information regarding the charge transport properties in semiconductors, its application for the characterization of low-conductive two-dimensional layers, i.e., σs < < 1 mS, remains elusive. This is primarily due to the low sensitivity of direct transmission measurements to such small sheet conductivity levels. In this work, we discuss harnessing the extraordinary optical transmission through gratings consisting of metallic stripes to characterize such low-conductive two-dimensional layers. We analyze the geometric tradeoffs in these structures and provide physical insights, ultimately leading to general design guidelines for experiments enabling non-contact, non-destructive, highly sensitive characterization of such layers.

Download Full-text