scholarly journals Benchmark PhotoIonization Cross-Sections of Neutral Scandium from the Ground and Excited States

Atoms ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 83
Author(s):  
Swaraj S. Tayal ◽  
Oleg Zatsarinny
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Energy Region ◽  
Bound States ◽  
Electron Ionization ◽  
Final State ◽  
Close Coupling ◽  
Resonance Structures ◽  
The Cross ◽  
Ionic States

The B-spline R-matrix method has been used to investigate cross-sections for photoionization of neutral scandium from the ground and excited states in the energy region from the 3d and 4s valence electron ionization thresholds to 25 eV. The initial bound states of Sc and the final residual Sc+ ionic states have been accurately calculated by combining the multiconfiguration Hartree-Fock method with the frozen-core close-coupling approach. The lowest 20 bound states of Sc I belonging to the ground 3d4s2 and excited 3d24s, 3d24p, 3d4s4p, 4s24p, and 3d3 configurations have been considered as initial states. The 81 LS final ionic states of Sc+ belonging to the terms of 3p63d2, 3p63d4l (l = 0–3), 3p63d5l (l = 0–3), 3p63d6s, 3p64s2, 3p64s4l (l = 0–3), 3p64s5l (l = 0–1), and 3p64p2 configurations have been included in the final-state close-coupling expansion. The cross-sections are dominated by complicated resonance structures in the low energy region converging to several Sc+ ionic thresholds. The inclusion of all these final ionic states has been noted to significantly impact the near-threshold resonance structures and background cross-sections. The important scattering channels for leaving the residual ion in various final states have been identified, and the 3d electron ionization channels have been noted to dominate the cross-sections at higher photon energies.

scholarly journals Partial Photoionization Cross Sections of Chromium from the Ground and Excited States

Atoms ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 51
Author(s):  
Oleg Zatsarinny ◽  
Swaraj Tayal
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Bound States ◽  
Close Coupling ◽  
R Matrix ◽  
Hartree Fock ◽  
Nonresonant Background ◽  
Ionic States ◽  
Matrix Calculation

Partial and total photoionization cross sections of iron-peak elements are important for the determination of abundances in late-type stars and nebular objects. We have investigated photoionization of neutral chromium from the ground and excited states in the low energy region from the first ionization threshold at 6.77 eV to 30 eV. Accurate descriptions of the initial bound states of Cr I and the final residual Cr II ionic states have been obtained in the multiconfiguration Hartree-Fock method together with adjustable configuration expansions and term-dependent non-orthogonal orbitals. The B-spline R-matrix method has been used for the calculation of photoionization cross sections. The 194 LS final ionic states of Cr II 3d44s, 3d34s2, 3d5, 3d44p, and 3d34s4p principal configurations have been included in the close-coupling expansion. The inclusion of all terms of these configurations has significant impact on the near-threshold resonance structures as well as on the nonresonant background cross sections. Total photoionization cross sections from the ground 3d54sa7S and excited 3d54sa5S, 3d44s2a5D, 3d54pz5P, and 3d44s4py5P states of Cr I have been compared with other available R-matrix calculation to estimate the likely uncertainties in photoionization cross sections. We analyzed the partial photoionization cross sections for leaving the residual ion in various states to identify the important scattering channels, and noted that 3d electron ionization channel becomes dominant at higher energies.

A measurement of the cross section for production of He + (2 S ) ions by electron impact excitation of ground state helium ions

1966 ◽  
Vol 290 (1420) ◽  
pp. 74-93 ◽  
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Cross Sections ◽  
Absolute Magnitude ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Close Coupling ◽  
Born Cross Section ◽  
The Absolute ◽  
The Cross

A crossed beams method has been used to measure the cross section for the production of He + (2 S ) by electrons incident upon He + (1 S ) in the energy range from threshold to 750 eV. The cross section was measured in arbitrary units with an accuracy of ± 5 % and at the higher energies its energy dependence is in close agreement with that calculated by means of the plane-wave Born approximation. Consequently the cross section has been normalized to the plane-wave Born cross section at energies between 435 and 750 eV to obtain the absolute magnitude. An independent estimate of the absolute magnitude was made to with in ± 30 % using only the experimental parameters, and the absolute cross sections given by the two methods agree within the experimental uncertainties. The normalized cross section is compared with cross sections given by the close-coupling approximation and various Coulomb-Born approximations. At the lower energies the normalized cross section is considerably smaller than any of the theoretical values, but the measurements are consistent with the existence of a finite cross section at threshold if the energy spread of the electron beam is taken in to account.

Optische Anregung beim Ladungsaustausch von Edelgasionen für Stoßenergien von 5 bis 300 eVolt

1968 ◽  
Vol 23 (7) ◽  
pp. 970-978
Author(s):  
H. Schlumbohm
Keyword(s):  
Charge Transfer ◽  
Kinetic Energy ◽  
Internal Energy ◽  
Excited States ◽  
Cross Sections ◽  
Ground Level ◽  
High Rate ◽  
Transfer Processes ◽  
The Cross ◽  
Threshold Energies

Measurements of the photoemission caused by collisions of ground level He+- and Ne+-ions with Ar- and Kr-atoms have shown several multipletts of Ar II and Kr II within the investigated wavelength range of 3500 to 5500 A. At a high rate the charge transfer processes occur into excited states of Ar* and Kr*. The reactions are endothermic with a deficit of internal energy between 6 and 19 eV.The cross sections measured for several chosen transitions start at characteristic threshold energies between 10 and 25 eV. Above the threshold the cross sections rise slowly with increasing energy when Ne* is the colliding ion and very fast for He+. Above 50 to 100 eV the cross sections show nearly constant values. — The minimum kinetic energy values are calculated, which can just fill up the deficits of internal energy, and are shown to be equal to the measured threshold energies. Thus it follows that the pseudo-crossing of the potential energy curves of the quasimolecules occurs at an energy value equal to the asymptotic level of the above curve.

Réactions 3He + 9Be, d + 10B → 3α et excitation du 12C dans la région 29–34 MeV

1977 ◽  
Vol 55 (23) ◽  
pp. 2113-2120 ◽  
Author(s):  
G. Goulard ◽  
R. Roy ◽  
R. J. Slobodrian
Keyword(s):  
Excited States ◽  
Energy Region ◽  
Energy Spectra ◽  
Two Stage ◽  
Final State ◽  
New Information ◽  
Stage Process ◽  
Α Particles

Excited states of 12C between 29 and 34 MeV are studied through the 3He + 9Be and d + 10B reactions leading to three α particles in the final state. Correlated energy spectra are analyzed with a two-stage process and new information is given about the studied excited energy region.

Excited states of positronium in positron–hydrogen charge exchange

1978 ◽  
Vol 56 (5) ◽  
pp. 565-570 ◽  
Author(s):  
V. S. Kulhar ◽  
C. S. Shastry
Keyword(s):  
Excited States ◽  
Charge Exchange ◽  
Cross Sections ◽  
Ground State ◽  
Born Approximation ◽  
Energy Region ◽  
Hydrogen Charge ◽  
Positronium Formation ◽  
State Approximation ◽  
Higher Excited States

The two state approximation method for the study of the rearrangement collisions is applied to the process of positronium formation in excited states for positron–hydrogen charge exchange collisions. Differential and integrated cross sections are computed for positronium formation in 2S, 2P, and 3S excited states. The results obtained in the energy region 2 to 10 Ry are compared with positronium formation cross sections in ground state. Total positronium formation cross sections including the contributions of capture into all the higher excited states of positronium are also computed in the first Born approximation and the two state approximation in the energy region considered.

scholarly journals Electron Scattering from the Ground and Excited States of Barium

1999 ◽  
Vol 52 (3) ◽  
pp. 603
Author(s):  
Dmitry V. Fursa
Keyword(s):  
Excited States ◽  
Electron Scattering ◽  
Cross Sections ◽  
Differential Cross ◽  
Ground State ◽  
Differential Cross Sections ◽  
Close Coupling ◽  
Angular Correlations ◽  
Electron Photon ◽  
Good Agreement

We have used the nonrelativistic convergent close-coupling (CCC) method to investigate electron scattering from the ground (6s2)1S state and excited (6s6p)1 Po1 and (6s5d)1,3De2 states of barium. For the scattering from the barium ground state, we have found very good agreement with measurements of (6s6p)1 Po1 apparent cross sections at all energies. Similarly, good agreement is found for differential cross sections for elastic scattering and (6s6p)1 Po and (6s5d)1 De2 excitations and with the (6s6p)1 Po1 state electron{photon angular correlations. For the scattering from excited states of barium we have found good agreement with elastic (6s6p)1 Po1 scattering and the (6s5d)1De2 → (6s6p)1 Po1 transition for both differential cross sections and electron–photon angular correlations.

Influence of final-state interaction on double spin asymmetries in incoherent π+-photoproduction on the deuteron near threshold

2020 ◽  
Vol 29 (08) ◽  
pp. 2050056
Author(s):  
E. M. Darwish ◽  
H. M. Al-Ghamdi
Keyword(s):  
Cross Sections ◽  
Energy Region ◽  
Final State Interaction ◽  
Reaction Model ◽  
Final State ◽  
Total Cross Sections ◽  
Spin Asymmetries ◽  
Double Spin ◽  
Final State Interactions ◽  
Near Threshold

Incoherent [Formula: see text]-photoproduction on the deuteron is investigated for photon energies near threshold with particular focus on beam-target double spin asymmetries. The analysis is based on a [Formula: see text] reaction model in which realistic elementary amplitudes for [Formula: see text], [Formula: see text] and [Formula: see text] are incorporated. Numerical results on all possible beam-target double spin asymmetries of the differential and total cross-sections in the photon energy region near threshold are presented. Effects of [Formula: see text] and [Formula: see text] final-state interactions are investigated and their roles are found to be important.

DOUBLE EXCITATION IN PROTON–HELIUM COLLISIONS

1995 ◽  
Vol 09 (25) ◽  
pp. 3269-3301 ◽  
Author(s):  
M. SCHULZ
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Experimental Studies ◽  
Projectile Energy ◽  
Interference Effects ◽  
Double Excitation ◽  
Doubly Excited States ◽  
Doubly Excited ◽  
Excitation Mechanisms ◽  
The Cross

Theoretical and experimental studies on double excitation in proton–helium collisions are reviewed. Two theoretical approaches, which are common in the treatment of atomic collision processes, are described: perturbative approaches and the close coupling method. Experimentally, double excitation has mainly been studied by spectroscopy of the autoionized electrons emitted by the decay of the doubly excited states and by projectile energy-loss spectroscopy. The results emerging from the theoretical and experimental studies include the following points: first, the coupling of the doubly excited states to the continuum is very important in the electron spectra leading to pronounced interference effects. Second, double excitation mechanisms involving the electron–electron interaction are dominant except for low projectile energies. Third, interference effects between various double excitation mechanisms appear to be insignificant in the cross-sections differential in the electron emission angle, but might be important under certain conditions in the cross-sections differential in the projectile scattering angle.

scholarly journals Test of QCD at large Q2 with exclusive hadronic processes

2014 ◽  
Vol 31 ◽  
pp. 1460304
Author(s):  
Chengping Shen ◽  
Keyword(s):  
Perturbative Qcd ◽  
Cross Sections ◽  
Branching Fractions ◽  
Center Of Mass ◽  
Axial Vector ◽  
Hadronic Decays ◽  
Final States ◽  
Final State ◽  
The Cross ◽  
Using Data

My report consists of two parts: (1). Using samples of 102 million ϒ(1S) and 158 million ϒ(2S) events at Belle, we study 17 exclusive hadronic decays of these two bottomonium resonances to some Vector-Pseudoscalar (VP), Vector-Tensor (VT) and Axial-vector-Pseudoscalar (AP) processes and their final states. Branching fractions are measured for all the processes. The ratios of the branching fractions of ϒ(2S) and ϒ(1S) decays into the same final state are used to test a perturbative QCD (pQCD) prediction for OZI-suppressed bottomonium decays. (2). Using data samples of 89 fb-1, 703 fb-1, and 121 fb-1 collected at center-of-mass (CMS) energies 10.52, 10.58, and 10.876 GeV, respectively, we measure the cross sections of e+e- → ωπ0, [Formula: see text], and [Formula: see text]. The energy dependence of the cross sections is presented.

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