Determination of the Difference Potential from Resonant Charge-Exchange Total Cross Sections: Analysis of RB+-Rb andCs+-Cs

1969 ◽  
Vol 187 (1) ◽  
pp. 153-161 ◽  
Author(s):  
R. E. Olson
Keyword(s):  
Charge Exchange ◽  
Cross Sections ◽  
Total Cross Sections ◽  
Resonant Charge Exchange ◽  
The Difference

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

Destruction of C2H4O2 isomers in ice-phase by X-rays: Implication on the abundance of acetic acid and methyl formate in the interstellar medium

2017 ◽  
Vol 13 (S332) ◽  
pp. 418-424
Author(s):  
Marina G. Rachid ◽  
K. Faquine ◽  
S. Pilling
Keyword(s):  
Acetic Acid ◽  
Cross Sections ◽  
Methyl Formate ◽  
X Rays ◽  
Formation Cross Section ◽  
X Ray ◽  
Synchrotron Light ◽  
The Difference ◽  
Astrophysical Ices

AbstractC2H4O2 isomers, methyl formate (HCOOCH3), acetic acid (CH3COOH) and glycoaldehyde (HOCH2CHO), have been detected in a lot of sources in ISM. However, their abundances are very different, with methyl formate much more abundant than the other two isomers. This fact may be related to the different destruction by ionizing radiation of these molecules. The goal of this work is experimentally study the photodissociation processes of methyl formate and acetic acid ices when exposed to broadband soft X-ray from 6 up to 2000 eV. The experiments were performed coupled to the SGM beamline in the Brazilian Synchrotron Light Source (LNLS/CNPEM) at Campinas, Brazil. The simulated astrophysical ices (12K) were monitored throughout the experiment using infrared vibrational spectroscopy. The analysis of processed ices allowed the determination of the effective destruction cross sections of the parent molecules as well as the effective formation cross section of daughter molecular species. The relative abundance between acetic acid and methyl formate (NCH3COOH/NHCOOCH3) in different astronomical scenarios and their column density evolution in the presence of X-rays were calculated and our results suggests that such radiation field can be one of the factors that explain the difference in the isomers C2H4O2 abundances. We also quantified the daugther species after the establishment of a chemical equilibrium in the samples.

scholarly journals Classical Description of Resonant Charge Exchange Involving the Second Flavor of Hydrogen Atoms

Atoms ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 41
Author(s):  
Eugene Oks
Keyword(s):  
Perturbation Theory ◽  
Electric Field ◽  
Charge Exchange ◽  
Cross Sections ◽  
Stark Effect ◽  
Uniform Electric Field ◽  
Hydrogen Atoms ◽  
Additional Tool ◽  
Classical Description ◽  
Resonant Charge Exchange

We studied the consequences of the existence of the second flavor of hydrogen atoms (SFHA)—the existence proven by atomic experiments and evidenced by astrophysical observations—on the resonant charge exchange. We found analytically that there is indeed an important difference in the corresponding cross-sections for the SFHA compared to the usual hydrogen atoms. This difference could serve as an additional tool for distinguishing between the two kinds of hydrogen atoms in future experiments/observations. We also show that the SFHA does not exhibit any Stark effect—whether in a uniform or a non-uniform electric field—in any order of the perturbation theory.

THE ADLER-WEISBERGER SUM RULE AND gA IN THE LARGE-N EXPANSION

1992 ◽  
Vol 01 (02) ◽  
pp. 301-309 ◽  
Author(s):  
M. SOLDATE
Keyword(s):  
Cross Sections ◽  
Direct Calculation ◽  
Skyrme Model ◽  
Sum Rule ◽  
Total Cross Sections ◽  
Large N ◽  
Nonrelativistic Quark Model ◽  
The Difference ◽  
Higher Order Corrections ◽  
Large N Expansion

The consistency of the Adler-Weisberger sum rule in the large-N expansion is examined. It is shown that the Δ saturates the sum rule in the nonrelativistic quark model to all orders in [Formula: see text] and in the Skyrme model to leading order in [Formula: see text]. Phenomenologically, it is evident that either gA or the integral over the difference of πp total cross sections appearing in the sum rule is poorly behaved as an expansion in [Formula: see text]. In the Skyrme model, based on the calculation of the Δ contribution to the sum rule, it appears that it is gA itself which has large higher-order corrections. It seems likely that in a direct calculation of gA, it it is necessary to include the first two subleading orders before an accurate result for gA can be obtained.

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