The 4d–4p transitions and soft X-ray laser wavelengths in Si-like ions

2013 ◽  
Vol 91 (11) ◽  
pp. 981-993 ◽  
Author(s):  
A. Abou El-Maaref ◽  
M.A.M. Uosif ◽  
S.H. Allam ◽  
Th.M. El-Sherbini
Keyword(s):  
Ionization Potential ◽  
Calculated Data ◽  
Laser Wavelength ◽  
Gain Factor ◽  
Oscillator Strengths ◽  
Rate Coefficients ◽  
Excitation Rate ◽  
X Ray ◽  
Laser Parameters

The transitions between 4p and 4d levels have been studied to examine the possibility of laser wavelength production in the soft X-ray region. The oscillator strengths of the transitions 3p4p (3S,3P,3D) → 3p4d (3Po,3Do,3Fo) have been calculated using CIV3 code. Using calculated oscillator strengths, the excitation rate coefficients, reduced populations, and gain coefficients for Si-like Ni XV, Zn XVII, Ga XVIII, Ge XIX, and As XX at electron temperatures 1/4, 1/2, and 3/4 the ionization potential have been calculated. The method by Palumbo and Elton has been used in the calculation of laser parameters. The present calculated data show promising values for the production of laser wavelengths in the soft X-ray region. The maximum values of the gain factor lie within the range α ∼ 109 cm−1 and wavelength λ ≤ 469 Å.

Laser gain calculations for soft X-ray and XUV radiation emitted from copper-like ions by electron collisional pumping

2016 ◽  
Vol 94 (10) ◽  
pp. 967-974
Author(s):  
Mohamed A. Sayed ◽  
Sami H. Allam ◽  
Tharwat M. El-Sherbini
Keyword(s):  
Transition Probabilities ◽  
Calculated Data ◽  
Level Population ◽  
Oscillator Strengths ◽  
Impact Excitation ◽  
Rate Coefficients ◽  
Electron Impact Excitation ◽  
Population Densities ◽  
Excitation Rate ◽  
X Ray

Electron impact excitation rate coefficients, level population densities, and gain coefficients for six excited ions with Z = 51, 52, 53, 54, 55, 56 in the copper isoelectronic sequence have been calculated. The electron collisional excitation rate coefficients are calculated according to the analytical formulas of Vriens and Smeets. Fine structure energy levels, transition probabilities, and oscillator strengths needed in the calculations have been calculated using Cowan atomic structure code with relativistic corrections for [Ar]3d10nl with n = 4–7 and l = 0–6. The level population densities are calculated by solving the coupled rate equations involving 30 levels. Positive gain coefficients of the possible emitted lines are obtained at three selected electron temperatures, namely 1/4, 1/2, and 3/4 of the ionization energy. The present calculated data show promising values for the production of soft X-ray and XUV laser by collisional pumping for the transitions 5p–5s and 6d–5f with wavelengths between 108 and 571 Å. The values of the maximum gain coefficient are found to increase with atomic number and their order of magnitude ranges from102to 104cm−1.

Calculated data on electron transport and excitation rate coefficients in and discharges

1997 ◽  
Vol 6 (2) ◽  
pp. 220-230 ◽  
Author(s):  
V Guerra ◽  
M J Pinheiro ◽  
B F Gordiets ◽  
J Loureiro ◽  
C M Ferreira
Keyword(s):  
Electron Transport ◽  
Calculated Data ◽  
Rate Coefficients ◽  
Excitation Rate

scholarly journals BASECOL2020 New Technical Design

Atoms ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 69 ◽  
Author(s):  
Yaye-Awa Ba ◽  
Marie-Lise Dubernet ◽  
Nicolas Moreau ◽  
Carlo Maria Zwölf
Keyword(s):  
Interstellar Medium ◽  
Data Center ◽  
Molecular Data ◽  
International Standards ◽  
Rate Coefficients ◽  
Collisional Excitation ◽  
Excitation Rate ◽  
Single Location ◽  
Molecular Databases ◽  
Key Features

The BASECOL database has been created and scientifically enriched since 2004. It contains collisional excitation rate coefficients of molecules for application to the interstellar medium and to cometary atmospheres. Recently, major technical updates have been performed in order to be compliant with international standards for management of data and in order to provide a more friendly environment to query and to present the data. The current paper aims at presenting the key features of the technical updates and to underline the compatibility of BASECOL database with the Virtual Atomic and Molecular Data Center. This latter aims to interconnect atomic and molecular databases, thus providing a single location where users can access atomic and molecular data.

scholarly journals X-ray laser lines in nickel-like erbium

2016 ◽  
Vol 94 (8) ◽  
pp. 705-711
Author(s):  
Wessameldin S. Abdelaziz
Keyword(s):  
Ionization Potential ◽  
Excited States ◽  
Ground State ◽  
Energy Levels ◽  
Single Electron ◽  
Electron Densities ◽  
X Ray ◽  
Electron Excited States

Energy levels of 249 excited levels in nickel-like erbium are calculated using the 3s23p63d10 as a ground state and the single electron excited states from n = 3 to n = 4, 5 orbitals, calculations have been performed using FAC code (Gu. Astrophys. J. 582, 1241 (2003). doi:10.1086/344745 ). The populations are calculated over electron densities from 1020 to 1023 cm−3 and electron temperatures 1/2, 3/4 of the ionization potential of Ni-like Er. The gain coefficients of the transitions are calculated.

scholarly journals Subsite mapping of enzymes. Depolymerase computer modelling

1976 ◽  
Vol 159 (1) ◽  
pp. 105-120 ◽  
Author(s):  
J D Allen ◽  
J A Thoma
Keyword(s):  
Goodness Of Fit ◽  
Computer Modelling ◽  
Bond Cleavage ◽  
Calculated Data ◽  
Simulated Data ◽  
Binding Energies ◽  
Rate Coefficients ◽  
Minimization Procedure ◽  
Squared Residuals ◽  
Subsite Mapping

We have developed a depolymerase computer model that uses a minimization routine. The model is designed so that, given experimental bond-cleavage frequencies for oligomeric substrates and experimental Michaelis parameters as a function of substrate chain length, the optimum subsite map is generated. The minimized sum of the weighted-squared residuals of the experimental and calculated data is used as a criterion of the goodness-of-fit for the optimized subsite map. The application of the minimization procedure to subsite mapping is explored through the use of simulated data. A procedure is developed whereby the minimization model can be used to determine the number of subsites in the enzymic binding region and to locate the position of the catalytic amino acids among these subsites. The degree of propagation of experimental variance into the subsite-binding energies is estimated. The question of whether hydrolytic rate coefficients are constant or a function of the number of filled subsites is examined.

EVALUATION OF THE STRESSED DEFORMED STATE OF MAIN GAS PIPELINES RUNNING IN PERMANENTLY FROZEN GROUNDS

2020 ◽  
pp. 58-63
Author(s):  
M. M. Sidorov ◽  
N. I. Golikov ◽  
R. P. Tihonov
Keyword(s):  
Experimental Data ◽  
Calculated Data ◽  
Gas Pipeline ◽  
Loss Of Stability ◽  
Portable Equipment ◽  
Ray Method ◽  
X Ray ◽  
Deformed State ◽  
Pipeline Monitoring

The work evaluates the stress deformed state of the section of the interfield gas collecting main, running in permanently frozen grounds. The object of research is a section of a pipeline with an arched discharge formed as a result of loss of stability as a result of thermal erosion of permanently frozen grounds to disturbance of the vegetation cover. The determination of stresses was carried out by the X-ray method using portable equipment. The experimental data were analyzed with the calculated. The calculated data were obtained by measuring the spatial position of the gas pipeline section. The obtained values of the acting stresses and the estimates of the critical indicators of the gas pipeline monitoring section made it possible to reasonably estimate the stress state. The methodology for determining the acting stresses of pipelines using portable X-ray equipment can be successfully applied to estimate the stressed-deformed state of pipeline systems running in the zone of permafrost.

Oscillator strength study of the excitations of valence-shell of C2H2 by high-resolution inelastic x-ray scattering

2021 ◽  
Author(s):  
Qiang Sun ◽  
Ya-Wei Liu ◽  
Yuan-Chen Xu ◽  
Li-Han Wang ◽  
Tian-Jun Li ◽  
...  
Keyword(s):  
High Resolution ◽  
Theoretical Models ◽  
High Energy ◽  
Oscillator Strengths ◽  
Electron Collision ◽  
Valence Shell ◽  
X Ray ◽  
X Ray Scattering ◽  
Theoretical Results ◽  
Ray Scattering

Abstract The oscillator strengths of the valence-shell excitations of C2H2 are extremely important for testing theoretical models and studying interstellar gases. In this study, the high-resolution inelastic x-ray scattering (IXS) method is adopted to determine the generalized oscillator strengths (GOSs) of the valence-shell excitations of C2H2 at a photon energy of 10 keV. The GOSs are extrapolated to their zero limit to obtain the corresponding optical oscillator strengths (OOSs). Through taking a completely different experimental method of the IXS, the present results offer the high energy limit for electron collision to satisfy the first Born approximation (FBA) and cross-check the previous experimental and theoretical results independently. The comparisons indicate that an electron collision energy of 1500 eV is not enough for C2H2 to satisfy the FBA for the large squared momentum transfer, and the line saturation effect limits the accuracy of the OOSs measured by the photoabsorption method.

scholarly journals Successes and Difficulties in Calculating Atomic Oscillator Strengths and Transition Rates

Galaxies ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 77 ◽  
Author(s):  
Alan Hibbert
Keyword(s):  
Interstellar Medium ◽  
Ab Initio ◽  
Atomic Structure ◽  
Plasma Diagnostics ◽  
Calculated Data ◽  
Stellar Atmospheres ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Transition Rates ◽  
Laboratory Measurements

There is an on-going need for accurate oscillator strengths to be used in astrophysical applications, particularly in plasma diagnostics and in the modelling of stellar atmospheres and the interstellar medium. There are several databases in regular use which contain some of the required data, although often insufficiently complete, and sometimes not sufficiently accurate. In addition, several atomic structure packages are available through the literature, or from their individual authors, which would allow further calculations to be undertaken. Laboratory measurements provide an important check on the accuracy of calculated data, and the combined efforts of theorists and experimentalists have succeeded in providing data of an accuracy sufficient for some astrophysical applications. However, the insufficiency or inadequacy of atomic data is a continuing problem. We discuss in the context of appropriate examples some of the principal steps which researchers have taken to calculate accurate oscillator strengths, including both ab initio results and also various extrapolation processes which attempt to improve such results. We also present some examples of the main causes of difficulty in such calculations, particularly for complex (many-electron) ions, and indicate ways in which the difficulties might be overcome.

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