A differential retarding potential method for the study of the energy distribution of slow electron emissions

1927 ◽  
Vol 23 (8) ◽  
pp. 922-929 ◽  
Author(s):  
C. F. Sharman
Keyword(s):  
Energy Distribution ◽  
Potential Method ◽  
Copper Surface ◽  
Secondary Emission ◽  
Good Resolution ◽  
Slow Electron ◽  
Secondary Electrons ◽  
Wide Range ◽  
Energy Distribution Curve ◽  
Electron Emissions

The method described gives the differential energy distribution curve directly from readings of a galvanometer and a voltmeter. When adjusted, the arrangement is convenient in operation and very good “resolution” can be obtained. The existence of a maximum frequency of secondary electrons at a finite small energy has been established, and its position is shown to be independent of the energy of the primary beam over a fairly wide range. The effect of deposition of tungsten on a clean copper surface is studied with respect to the secondary emission properties of the surface. From these experiments some interesting conclusions concerning the mechanism of the process may be drawn.I am very grateful to Prof. Sir Ernest Rutherford for the encouragement he has given and the interest he has taken in this work.

Analysis of Contrast Reversal in SEM Images

1972 ◽  
Vol 30 ◽  
pp. 398-399
Author(s):  
M. D. Coutts ◽  
E. R. Levin
Keyword(s):  
Incident Beam ◽  
Normal Incidence ◽  
Beam Current ◽  
Secondary Emission ◽  
Image Contrast ◽  
Sem Images ◽  
Secondary Electrons ◽  
Image Position

On tilting samples in an SEM, the image contrast between two elements, x and y often decreases to zero at θε, which we call the no-contrast angle. At angles above θε the contrast is reversed, θ being the angle between the specimen normal and the incident beam. The available contrast between two elements, x and y, in the SEM can be defined as,(1)where ix and iy are the total number of reflected and secondary electrons, leaving x and y respectively. It can easily be shown that for the element x,(2)where ib is the beam current, isp the specimen absorbed current, δo the secondary emission at normal incidence, k is a constant, and m the reflected electron coefficient.

Validated Stability Indicating HPTLC Method for the Estimation of Amoxapine in Different Stress Conditions

2019 ◽  
Vol 15 (3) ◽  
pp. 273-279
Author(s):  
Shweta G. Rangari ◽  
Nishikant A. Raut ◽  
Pradip W. Dhore
Keyword(s):  
High Performance ◽  
Limit Of Detection ◽  
Degradation Products ◽  
Analysis Data ◽  
Peak Height ◽  
Good Resolution ◽  
Stability Indicating ◽  
Limit Of Quantitation ◽  
Wide Range ◽  
Hptlc Method

Background:The unstable and/or toxic degradation products may form due to degradation of drug which results into loss of therapeutic activity and lead to life threatening condition. Hence, it is important to establish the stability characteristics of drug in various conditions such as in temperature, light, oxidising agent and susceptibility across a wide range of pH values.Introduction:The aim of the proposed study was to develop simple, sensitive and economic stability indicating high performance thin layer chromatography (HPTLC) method for the quantification of Amoxapine in the presence of degradation products.Methods:Amoxapine and its degraded products were separated on precoated silica gel 60F254 TLC plates by using mobile phase comprising of methanol: toluene: ammonium acetate (6:3:1, v/v/v). The densitometric evaluation was carried out at 320 nm in reflectance/absorbance mode. The degradation products obtained as per ICH guidelines under acidic, basic and oxidative conditions have different Rf values 0.12, 0.26 and 0.6 indicating good resolution from each other and pure drug with Rf: 0.47. Amoxapine was found to be stable under neutral, thermal and photo conditions.Results:The method was validated as per ICH Q2 (R1) guidelines in terms of accuracy, precision, ruggedness, robustness and linearity. A good linear relationship between concentration and response (peak area and peak height) over the range of 80 ng/spot to 720 ng/spot was observed from regression analysis data showing correlation coefficient 0.991 and 0.994 for area and height, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) for area were found to be 1.176 ng/mL and 3.565 ng/mL, whereas for height, 50.063 ng/mL and 151.707 ng/mL respectively.Conclusion:The statistical analysis confirmed the accuracy, precision and selectivity of the proposed method which can be effectively used for the analysis of amoxapine in the presence of degradation products.

Fabrication of periodic microscale stripes of silver by laser interference induced forward transfer and their SERS properties

2021 ◽  
Author(s):  
Huijuan Shen ◽  
Yaode Wang ◽  
Liang Cao ◽  
Ying Xie ◽  
Lu Wang ◽  
...  
Keyword(s):  
Film Thickness ◽  
Laser Fluence ◽  
Nano Particles ◽  
Good Resolution ◽  
Laser Interference ◽  
Ag Nps ◽  
Wide Range ◽  
Forward Transfer ◽  
Stripe Structure ◽  
Average Size

Abstract The micro-stripe structure was prepared by laser interference induced forward transfer (LIIFT) technique, composed of Ag nano-particles (NPs). The effects of the film thickness with the carbon nano-particles mixed polyimide (CNPs@PI), Ag film thickness, and laser fluence were studied on the transferred micro-stripe structure. The periodic Ag micro-stripe with good resolution was obtained in a wide range of CNPs@PI film thickness from ~ 0.5 μm to ~ 1.0 μm for the Ag thin film ~ 20 nm. The distribution of the Ag NPs composing the micro-stripe was compact. Nevertheless, the average size of the transferred Ag NPs was increased from ~ 41 nm to ~ 197 nm with the change of the Ag donor film from ~ 10 nm to ~ 40 nm. With the increase of the laser fluence from 102 mJ•cm-2 to 306 mJ•cm-2 per-beam, the transferred Ag NPs became aggregative, improving the resolution of the corresponding micro-stripe. Finally, the transferred Ag micro-stripe exhibited the significant surface enhanced Raman scattering (SERS) property for rhodamine B (RhB). While the concentration of the RhB reached 10-10 mol•L-1, the Raman characteristic peaks of the RhB were still observed clearly at 622 cm-1, 1359 cm-1, and 1649 cm-1. These results indicate that the transferred Ag micro-stripe has potential application as a SERS chip in drug and food detection.

scholarly journals Cosmic Ray Induced Photodestruction of Interstellar Molecules

1989 ◽  
Vol 120 ◽  
pp. 32-37
Author(s):  
R. Gredel ◽  
S. Lepp ◽  
A. Dalgarno ◽  
E. Herbst
Keyword(s):  
Molecular Hydrogen ◽  
Cosmic Ray ◽  
Impact Excitation ◽  
Interstellar Molecules ◽  
Secondary Electrons ◽  
Interstellar Clouds ◽  
Wide Range ◽  
Ultraviolet Photons ◽  
The Impact ◽  
Equilibrium Chemical

AbstractUltraviolet photons are created in the interior of dense interstellar clouds by the impact excitation of molecular hydrogen by secondary electrons generated by cosmic ray ionization. The resulting photodissociation and photoionization rates of a wide range of interstellar molecules are calculated. The effects on the equilibrium chemical composition of dense clouds are briefly discussed.

Measurement of structure in the energy distribution of slow secondary electrons from aluminum

1976 ◽  
Vol 47 (7) ◽  
pp. 2941-2945 ◽  
Author(s):  
T. E. Everhart ◽  
N. Saeki ◽  
R. Shimizu ◽  
T. Koshikawa
Keyword(s):  
Energy Distribution ◽  
Secondary Electrons

The Action of Positive Ions of Caesium on a Hot Nickel Surface

1931 ◽  
Vol 27 (4) ◽  
pp. 570-577 ◽  
Author(s):  
P. B. Moon
Keyword(s):  
Incident Beam ◽  
Normal Incidence ◽  
Industrial Research ◽  
Secondary Emission ◽  
Nickel Surface ◽  
Target Temperature ◽  
Secondary Electrons ◽  
Positive Ions ◽  
Hot Target

Experiments on the emission of secondary electrons from hot nickel surfaces bombarded by Cs+ ions at normal incidence show that the emission is a function of bombarding voltage and target temperature. The emission is negligible below 300 volts and increases steadily with further increase of the bombarding voltage, rising to 4% at 4000 volts with the target at 950° C. Increase of temperature causes the secondary emission to diminish. If positive ions are allowed to evaporate from the hot target the number of Cs+ ions leaving the surface may, under certain conditions, be equal (with an accuracy greater than 1%) to the number arriving in the incident beam.I much appreciate the kindness shown me in many ways by Lord Rutherford. The experiments were commenced at the instigation of Dr M. L. E. Oliphant and I gratefully acknowledge that this paper represents to a great extent the results of his advice and assistance. The work was made possible by a grant from the Department of Scientific and Industrial Research.

Formation of Anticyclones above Topographic Depressions

2021 ◽  
Vol 51 (1) ◽  
pp. 207-228
Author(s):  
Aviv Solodoch ◽  
Andrew L. Stewart ◽  
James C. McWilliams
Keyword(s):  
Energy Distribution ◽  
Numerical Simulations ◽  
North Atlantic ◽  
Potential Vorticity ◽  
Circulation Pattern ◽  
Nonlinearity Parameter ◽  
Wide Range ◽  
Anticyclonic Eddies ◽  
Topographic Depressions ◽  
Pv Gradient

AbstractLong-lived anticyclonic eddies (ACs) have been repeatedly observed over several North Atlantic basins characterized by bowl-like topographic depressions. Motivated by these previous findings, the authors conduct numerical simulations of the spindown of eddies initialized in idealized topographic bowls. In experiments with one or two isopycnal layers, it is found that a bowl-trapped AC is an emergent circulation pattern under a wide range of parameters. The trapped AC, often formed by repeated mergers of ACs over the bowl interior, is characterized by anomalously low potential vorticity (PV). Several PV segregation mechanisms that can contribute to the AC formation are examined. In one-layer experiments, the dynamics of the AC are largely determined by a nonlinearity parameter ϵ that quantifies the vorticity of the AC relative to the bowl’s topographic PV gradient. The AC is trapped in the bowl for low , but for moderate values () partial PV segregation allows the AC to reside at finite distances from the center of the bowl. For higher , eddies freely cross the topography and the AC is not confined to the bowl. These regimes are characterized across a suite of model experiments using ϵ and a PV homogenization parameter. Two-layer experiments show that the trapped AC can be top or bottom intensified, as determined by the domain-mean initial vertical energy distribution. These findings contrast with previous theories of mesoscale turbulence over topography that predict the formation of a prograde slope current, but do not predict a trapped AC.

MONTE CARLO CALCULATION OF THE ENERGY DISTRIBUTION OF BACKSCATTERED ELECTRONS

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4405-4412 ◽  
Author(s):  
Z. J. DING ◽  
X. D. TANG ◽  
H. M. LI
Keyword(s):  
Monte Carlo ◽  
Elastic Scattering ◽  
Energy Distribution ◽  
Cross Section ◽  
Monte Carlo Calculation ◽  
Simulation Method ◽  
Elastic Peak ◽  
Secondary Electrons ◽  
Backscattered Electrons ◽  
Cylindrical Mirror

The full energy distribution of backscattered electrons from elastic peak down to true secondary electron peak has been calculated by a Monte-Carlo simulation method by including cascade secondary electrons production. The simulation method is based on the use of a dielectric function for describing electron inelastic scattering and secondary excitation, and the use of Mott cross section for electron elastic scattering. This calculation reproduces well the backscattering background observed in the direct mode of AES. The calculated absolute electron yields have been compared with the available experimental data. The simulation has indicated that, due to the effect of the elastic scattering differential cross section and detection solid angles, the shape of the energy distribution measured with a cylindrical mirror analyzer may differ from the overall energy spectrum of emitted electrons.

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