Photo-induced structural changes in obliquely deposited arsenic-based amorphous chalcogenides: a model for photostructural changes

1999 ◽  
Vol 79 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Y. Kuzukawa, Ashtosh Ganjoo, K. Shimak
Keyword(s):  
Structural Changes ◽  
Amorphous Chalcogenides

Electron and Photon Irradiation Effects in Metal/Amorphous Chalcogenide Bilayers

1994 ◽  
Vol 337 ◽  
Author(s):  
Andreas Ploessl ◽  
B.J. Dhanjal ◽  
A.G. Fitzgerald ◽  
R.A.G. Gibson ◽  
A.D. Gillies
Keyword(s):  
Electron Beam ◽  
Ultraviolet Light ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
X Ray ◽  
Photon Irradiation ◽  
Amorphous Chalcogenides ◽  
Potential Benefits ◽  
Electron And Photon ◽  
Better Than

ABSTRACTThin film bilayers of metal and amorphous chalcogenides have been prepared by evaporation. The metals were silver and zinc, while the chalcogenides were P2Se3 and arsenic sulphides, mainly As2S3. The metals dissolved into the chalcogenide films when illuminated with ultraviolet light or when irradiated with an electron beam. The changes in composition and chemical bonding which were caused by this irradiation, were investigated by x-ray photoelectron spectroscopy. The concomitant structural changes have been investigated by electron diffraction.After the metal and chalcogenide had intermixed, either due to photon or electron irradiation, the layers became sensitive to an electron beam; this sensitivity depended on the composition of the chalcogenide. Energy-dispersive x-ray microanalysis showed that the electron beam rapidly, but reversibly, depleted the irradiated areas of the dissolved metal. Very fine patterns, of better than half-micron resolution, could be written. By exposing a pure arsenic sulphide film through a shadow mask to ultraviolet light, zinc could be deposited selectively to form fine patterns. Plasma processing developed either kind of pattern reliably, thus rendering the material a dry inorganic resist for photo- and electron-beam-lithography with potential benefits in particular for GaAs.

Kinetics of optically-induced crystallization and structure of Agx(As0.48S0.26Se0.26)100-x chalcogenide films.

2006 ◽  
Vol 918 ◽  
Author(s):  
Milos Krbal ◽  
Tomas Wagner ◽  
Miloslav Frumar ◽  
Milan Vlcek ◽  
Petr Bezdicka
Keyword(s):  
Thin Films ◽  
Structural Changes ◽  
Phase Changes ◽  
Chalcogenide Films ◽  
Amorphous Chalcogenides ◽  
Industrial Dimension ◽  
Silver Dissolution ◽  
Kinetics Of ◽  
Induced Crystallization ◽  
Optically Induced

AbstractThe high density optical and/or thermal, electrical memories based on recording into chalcogenide thin films are currently used in industrial dimension but search for new materials continues due to request of higher recording density and shorter lasers wavelength available. The thin films of amorphous chalcogenides e.g. of Ag-As-S(Se) systems making or ternary use different techniques i.e. optically-induced silver dissolution in the binary As-S or As-S-Se chalcogenides prepared by thermal evaporation or by spin coating techniques were prepared and studied. Ternary Ag-As-S and quarternary Ag-As-S(Se) chalcogenide films were also deposited by direct-pulsed laser deposition. Films with euthectic or stoichiometric compositions were prepared. Optically-induced phase-changes in films, process kinetics and analysis of the structural changes and their potential application are described.

Fine Structural Changes in the Microvasculature of the Mouse Pinna: Aging and Radiation Injury

1974 ◽  
Vol 32 ◽  
pp. 54-55
Author(s):  
S. Phyllis Steamer ◽  
Rosemarie L. Devine
Keyword(s):  
Structural Changes ◽  
Radiation Treatment ◽  
Arterial Stenosis ◽  
Ultrastructural Changes ◽  
Vascular Effects ◽  
Microvascular Changes ◽  
Surrounding Connective Tissue ◽  
Fission Neutrons ◽  
Total Body

The importance of radiation damage to the skin and its vasculature was recognized by the early radiologists. In more recent studies, vascular effects were shown to involve the endothelium as well as the surrounding connective tissue. Microvascular changes in the mouse pinna were studied in vivo and recorded photographically over a period of 12-18 months. Radiation treatment at 110 days of age was total body exposure to either 240 rad fission neutrons or 855 rad 60Co gamma rays. After in vivo observations in control and irradiated mice, animals were sacrificed for examination of changes in vascular fine structure. Vessels were selected from regions of specific interest that had been identified on photomicrographs. Prominent ultrastructural changes can be attributed to aging as well as to radiation treatment. Of principal concern were determinations of ultrastructural changes associated with venous dilatations, segmental arterial stenosis and tortuosities of both veins and arteries, effects that had been identified on the basis of light microscopic observations. Tortuosities and irregularly dilated vein segments were related to both aging and radiation changes but arterial stenosis was observed only in irradiated animals.

Evaluation of single-electron movies of glutamine synthetase molecules

1983 ◽  
Vol 41 ◽  
pp. 280-281
Author(s):  
W. Kunath ◽  
E. Zeitler ◽  
M. Kessel
Keyword(s):  
Electron Microscope ◽  
Glutamine Synthetase ◽  
Electron Irradiation ◽  
Structural Damage ◽  
Structural Changes ◽  
Single Electron ◽  
Continuous Series ◽  
Digital Recording ◽  
Recording Device ◽  
Low Exposure

The features of digital recording of a continuous series (movie) of singleelectron TV frames are reported. The technique is used to investigate structural changes in negatively stained glutamine synthetase molecules (GS) during electron irradiation and, as an ultimate goal, to look for the molecules' “undamaged” structure, say, after a 1 e/Å2 dose.The TV frame of fig. la shows an image of 5 glutamine synthetase molecules exposed to 1/150 e/Å2. Every single electron is recorded as a unit signal in a 256 ×256 field. The extremely low exposure of a single TV frame as dictated by the single-electron recording device including the electron microscope requires accumulation of 150 TV frames into one frame (fig. lb) thus achieving a reasonable compromise between the conflicting aspects of exposure time per frame of 3 sec. vs. object drift of less than 1 Å, and exposure per frame of 1 e/Å2 vs. rate of structural damage.

Fine Structural Changes in the Adenohypophyses of Rats Following Destruction of the Pituitary Stalk

1977 ◽  
Vol 35 ◽  
pp. 496-497
Author(s):  
K. Kovacs ◽  
E. Horvath ◽  
J. M. Bilbao ◽  
F. A. Laszlo ◽  
I. Domokos
Keyword(s):  
Structural Changes ◽  
Tissue Injury ◽  
Anterior Lobe ◽  
Uranyl Acetate ◽  
Male Rats ◽  
Pituitary Stalk ◽  
Sequence Of Events ◽  
Pituitary Glands ◽  
Electrolytic Lesions ◽  
Ultrathin Sections

Electrolytic lesions of the pituitary stalk in rats interrupt adenohypophysial blood flow and result in massive infarction of the anterior lobe. In order to obtain a deeper insight into the morphogenesis of tissue injury and to reveal the sequence of events, a fine structural investigation was undertaken on adenohypophyses of rats at various intervals following destruction of the pituitary stalk.The pituitary stalk was destroyed electrolytically, with a Horsley-Clarke apparatus on 27 male rats of the R-Amsterdam strain, weighing 180-200 g. Thirty minutes, 1,2,4,6 and 24 hours after surgery the animals were perfused with a glutaraldehyde-formalin solution. The skulls were then opened and the pituitary glands removed. The anterior lobes were fixed in glutaraldehyde-formalin solution, postfixed in osmium tetroxide and embedded in Durcupan. Ultrathin sections were stained with uranyl acetate and lead citrate and investigated with a Philips 300 electron microscope.

Membrane Changes in Polymorphonuclear Leukocytes During Ionophore (A23187) - Induced Lysosomal Release

1977 ◽  
Vol 35 ◽  
pp. 482-483
Author(s):  
P.L. Moore ◽  
P.L. Sannes ◽  
H.L. Bank ◽  
S.S. Spicer
Keyword(s):  
Structural Changes ◽  
Calcium Release ◽  
Clear Understanding ◽  
Ionophore A23187 ◽  
Enzyme Release ◽  
Extracellular Medium ◽  
Pmn Leukocytes ◽  
Intracellular Ion Concentrations ◽  
Membrane Changes ◽  
Pmn Leukocyte

It is thought that calcium and/or magnesium may play important roles in polymorphonuclear (PMN) leukocyte functions such as chemotaxis, adhesion and phagocytosis. Yet, a clear understanding of the biological roles of these ions has awaited the development of techniques which permit a selective alteration of intracellular ion concentrations. Recently, treatment of cells with the ionophore A23187 has been used to alter intracellular divalent cation concentrations. This ionophore is a lipid soluble antibiotic produced by Streptomyces chartreusensis that complexes with both calcium and magnesium (3) and is believed to carry these ions across biological membranes (4). Biochemical investigations of human PMN leukocytes demonstrate that cells treated with A23187 and extracellular calcium release their lysosomal enzymes into the extracellular medium without rupturing and releasing their soluble cytoplasmic enzymes (5,6). The aim of the present study and and a companion report (7) was to investigate the structural changes that occur in leukocytes during ionophore-induced lysosomal enzyme release.

The Reaction of Brain Structures with OsO4-Zinc-Iodide Stain

1971 ◽  
Vol 29 ◽  
pp. 272-273
Author(s):  
Werner J. Niklowitz
Keyword(s):  
Electron Microscope ◽  
Structural Changes ◽  
Mossy Fiber ◽  
Toxic Metal ◽  
Staining Technique ◽  
Brain Structures ◽  
Oxidase Inhibitor ◽  
Fiber Layer ◽  
Hippocampal Tissue ◽  
Zinc Iodide

After intoxication of rabbits with certain substances such as convulsant agents (3-acetylpyridine), centrally acting drugs (reserpine), or toxic metal compounds (tetraethyl lead) a significant observation by phase microscope is the loss of contrast of the hippocampal mossy fiber layer. It has been suggested that this alteration, as well as changes seen with the electron microscope in the hippocampal mossy fiber boutons, may be related to a loss of neurotransmitters. The purpose of these experiments was to apply the OsO4-zinc-iodide staining technique to the study of these structural changes since it has been suggested that OsO4-zinc-iodide stain reacts with neurotransmitters (acetylcholine, catecholamines).Domestic New Zealand rabbits (2.5 to 3 kg) were used. Hippocampal tissue was removed from normal and experimental animals treated with 3-acetylpyridine (antimetabolite of nicotinamide), reserpine (anti- hypertensive/tranquilizer), or iproniazid (antidepressant/monamine oxidase inhibitor). After fixation in glutaraldehyde hippocampal tissue was treated with OsO4-zinc-iodide stain and further processed for phase and electron microscope studies.

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