Residual Gas Reactions in the Electron Microscope: IV. A Factor in Radiation Damage

1971 ◽  
Vol 29 ◽  
pp. 74-75
Author(s):  
Richard E. Hartman ◽  
Roberta S. Hartman
Keyword(s):  
Electron Microscope ◽  
Inelastic Scattering ◽  
Radiation Damage ◽  
Common Assumption ◽  
Step Process ◽  
One Step ◽  
The Common ◽  
Residual Gas ◽  
Gas Reactions ◽  
Dose Dependent

The common assumption that in the electron microscope there is a minimum, irreducible, dose-dependent damage to the specimen caused by inelastic scattering of electrons implies that such damage results from a one - step process. We now have evidence that this assumption is open to serious question.

Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

1968 ◽  
Vol 26 ◽  
pp. 292-293
Author(s):  
Richard E. Hartman ◽  
Roberta S. Hartman ◽  
Peter L. Ramos
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Gas Phase ◽  
Absolute Temperature ◽  
Residual Gas ◽  
Gas Reactions ◽  
Image Position ◽  
The Right ◽  
Water Gas ◽  
Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

scholarly journals Microscopic coupled-channel calculation of proton and alpha inelastic scattering to the 41+ and 42+ states of 24Mg

2021 ◽  
Author(s):  
Yoshiko Kanada-En'yo ◽  
Kazuyuki Ogata
Keyword(s):  
Inelastic Scattering ◽  
Cross Sections ◽  
Angular Distributions ◽  
Channel Calculation ◽  
Triaxial Deformation ◽  
Step Process ◽  
Coupled Channel Calculation ◽  
One Step ◽  
Coupled Channel ◽  
Α Particles

Abstract The triaxial and hexadecapole deformations of the Kπ = 0+ and Kπ = 2+ bands of 24Mg have been investigated by the inelastic scatterings of various probes, including electrons, protons, and alpha(α) particles, for a prolonged time. However, it has been challenging to explain the unique properties of the scatterings observed for the 41+ state through reaction calculations. This paper investigates the structure and transition properties of the Kπ = 0+ and Kπ = 2+ bands of 24Mg employing the microscopic structure and reaction calculations via inelastic proton and α scattering. In particular, the E4 transitions to the 41+ and 42+ states are reexamined. The structure of 24Mg was calculated employing the variation after the parity and total angular momentum projections in the framework of the antisymmetrized molecular dynamics (AMD). The inelastic proton and α reactions were calculated by the microscopic coupled-channel (MCC) approach by folding the Melbourne g-matrix NN interaction with the AMD densities of 24Mg. Reasonable results were obtained on the properties of the structure, including the energy spectra and E2 and E4 transitions of the Kπ = 0+ and Kπ = 2+ bands owing to the enhanced collectivity of triaxial deformation. The MCC+AMD calculation successfully reproduced the angular distributions of the 41+ and 42+ cross sections of proton scattering at incident energies of Ep = 40–100MeV and α scattering at Eα = 100–400 MeV. This is the first microscopic calculation to describe the unique properties of the 01+ → 41+ transition. In the inelastic scattering to the 41+ state, the dominant two-step process of the 01+→ 21+→ 41+ transitions and the deconstructive interference in the weak one-step process were essential.

Rapid Plasma-Assisted, Ambient-Pressure Deposition of Conformal Nanocrystalline Zinc Oxide Thin Films for Solar Cell Applications

2011 ◽  
Vol 1323 ◽  
Author(s):  
Joachim D. Pedersen ◽  
Kwok Siong Teh
Keyword(s):  
Deposition Temperature ◽  
Ambient Pressure ◽  
Zno Thin Film ◽  
Step Process ◽  
Fused Quartz ◽  
One Step ◽  
The Common ◽  
Deposited Films ◽  
Nanocrystalline Zinc Oxide ◽  
Made In

ABSTRACTThis paper reports a plasma-assisted, rapid, ambient-pressure, low-temperature one-step process for depositing conformal, non-porous nanocrystalline ZnO thin film on various substrates ranging from Si (100), fused quartz, glass, muscovite, c- and a-plane sapphire (Al2O3), to the common polymer polyimide (KaptonTM). The as-synthesized polycrystalline films range in thickness from 20nm to 200nm, deposited at a growth rate ranging from 2 nm/min to 50 nm/min. The lowest deposition temperature achieved with this method is 180°C and progress is being made in further lowering this temperature. The as-deposited films are highly oriented in the caxis, with (002) being the dominant planes.

‘Wake-Up Call of A Sleeping Beauty’: Straightforward Synthesis of Functionalized β-(2-Pyridyl) Ketones from 2,6-Lutidine

Synlett ◽  
2017 ◽  
Vol 28 (10) ◽  
pp. 1219-1223 ◽  
Author(s):  
Laure Bouchez ◽  
Cyril Gerbeaux ◽  
Marion Rusch ◽  
Maude Patoor ◽  
Madeleine Livendahl ◽  
...  
Keyword(s):  
Natural Products ◽  
Physicochemical Properties ◽  
Building Block ◽  
Sleeping Beauty ◽  
Starting Material ◽  
Step Process ◽  
Small Set ◽  
One Step ◽  
The Common

β-(2-Pyridyl) ketones are a unique class of heterocycles with valuable physicochemical properties and emerging relevance as pharmacophores. Herein we report a one-step process for the preparation of various substituted β-(2-pyridyl) ketones from the common starting material, 2,6-lutidine. Furthermore, we demonstrate the utility of this building block by synthesizing of a small set of antimalarial natural products.

Resolving Crystallites in Zirconium Oxide Films

1969 ◽  
Vol 27 ◽  
pp. 140-141
Author(s):  
R.A. Ploc
Keyword(s):  
Electron Microscope ◽  
Inelastic Scattering ◽  
Zirconium Oxide ◽  
Oxide Films ◽  
Optic Axis ◽  
Objective Lens ◽  
Microscope Objective ◽  
Linear Optic ◽  
A Current ◽  
Microscope Objective Lens

The optic axis of an electron microscope objective lens is usually assumed to be straight and co-linear with the mechanical center. No reason exists to assume such perfection and, indeed, simple reasoning suggests that it is a complicated curve. A current centered objective lens with a non-linear optic axis when used in conjunction with other lenses, leads to serious image errors if the nature of the specimen is such as to produce intense inelastic scattering.

Design of Sensitive Photographic Materials for the High-Voltage Electron Microscope

1975 ◽  
Vol 33 ◽  
pp. 156-157
Author(s):  
Murray Vernon King ◽  
Donald F. Parsons
Keyword(s):  
Electron Microscope ◽  
Radiation Damage ◽  
High Voltage ◽  
Radiation Sensitivity ◽  
Fast Electrons ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Biological Studies ◽  
Low Sensitivity

Effective application of the high-voltage electron microscope to a wide variety of biological studies has been restricted by the radiation sensitivity of biological systems. The problem of radiation damage has been recognized as a serious factor influencing the amount of information attainable from biological specimens in electron microscopy at conventional voltages around 100 kV. The problem proves to be even more severe at higher voltages around 1 MV. In this range, the problem is the relatively low sensitivity of the existing recording media, which entails inordinately long exposures that give rise to severe radiation damage. This low sensitivity arises from the small linear energy transfer for fast electrons. Few developable grains are created in the emulsion per electron, while most of the energy of the electrons is wasted in the film base.

Scanning Secondary Electron Microscopy of Myofibrils Using Transmission Techniques

1975 ◽  
Vol 33 ◽  
pp. 556-557
Author(s):  
M. K. Lamvik
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Carbon Films ◽  
Photographic Recording ◽  
Transmission Electron ◽  
Thin Carbon ◽  
The Common ◽  
Scanning Electron ◽  
Better Than ◽  
Cellular Organelles

When observing small objects such as cellular organelles by scanning electron microscopy, it is often valuable to use the techniques of transmission electron microscopy. The common practice of mounting and coating for SEM may not always be necessary. These possibilities are illustrated using vertebrate skeletal muscle myofibrils.Micrographs for this study were made using a Hitachi HFS-2 scanning electron microscope, with photographic recording usually done at 60 seconds per frame. The instrument was operated at 25 kV, with a specimen chamber vacuum usually better than 10-7 torr. Myofibrils were obtained from rabbit back muscle using the method of Zak et al. To show the component filaments of this contractile organelle, the myofibrils were partially disrupted by agitation in a relaxing medium. A brief centrifugation was done to clear the solution of most of the undisrupted myofibrils before a drop was placed on the grid. Standard 3 mm transmission electron microscope grids covered with thin carbon films were used in this study.

Platelet Adhesion to Native Collagens Involves Proteoglycans and May Be a Two-Step Process

1987 ◽  
Vol 58 (02) ◽  
pp. 786-789 ◽  
Author(s):  
O Behnke
Keyword(s):  
Electron Microscope ◽  
Platelet Adhesion ◽  
Close Contact ◽  
Blood Platelets ◽  
Collagen Fibrils ◽  
Platelet Membrane ◽  
Step Process ◽  
Rat Blood ◽  
Wide Gap ◽  
Rat Tail

SummaryAdhesion of rat blood platelets to native rat tail collagen fibrils was studied in the electron microscope under conditions that preserved collagen-associated proteoglycans (CAPG). The CAPG molecules were aligned in chain-like configurations that encircled the fibrils with a 65 nm period; they appeared to coat the fibrils completely and extended 60-100 nm away from the fibril. The initial platelet-fibril contact occurred between the platelet glycocalyx and the CAPG of the fibrils i.e. between two surfaces with net-negative charges. When close contact was established between the fibril surface proper and the platelet membrane, CAPG were not identified in the area of contact, and the collagen-platelet distance was reduced to a ~10-12 nm wide gap traversed by delicate links in register with fibril periodicities.

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