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.

Application of the two state approximation to positronium formation in hydrogen

1977 ◽  
Vol 55 (16) ◽  
pp. 1393-1398 ◽  
Author(s):  
V. S. Kulhar ◽  
C. S. Shastry
Keyword(s):  
Charge Exchange ◽  
Cross Sections ◽  
Energy Region ◽  
Hydrogen Charge ◽  
Time Dependent ◽  
Quantum Mechanical ◽  
High Energies ◽  
Mechanical Formalism ◽  
State Approximation ◽  
Quantum Mechanical Formalism

A generalized form of Band's theory for rearrangement collisions based on the two state approximation in time dependent quantum-mechanical formalism is used to investigate the positron hydrogen charge exchange problem. The formalism takes into account the nonorthogonality of the rearrangement channel. The effect of nonorthogonality is to raise the cross sections from first Born results. At high energies our results approach Born results. Comparison with other calculations is also reported in the energy region 1.5 to 10 Ry.

Formation of antihydrogen in the ground state

2007 ◽  
Vol 85 (4) ◽  
pp. 393-399
Author(s):  
V S Kulhar
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
Time Reversal ◽  
Exchange Process ◽  
Hydrogen Charge ◽  
High Energy ◽  
High Energy Region ◽  
Charge Exchange Process ◽  
State Approximation ◽  
Reversal Invariance

Cross sections for antihydrogen formation in the ground state for the process [Formula: see text] + Ps(nlm) → [Formula: see text](1s) + e– have been calculated using charge conjugation and time reversal invariance. Calculations are based on a two-state approximation method, used by the author earlier for positron–hydrogen charge -exchange process (e+ – H → Ps(nlm) + p). Cross-section results are reported in the intermediate- and high-energy region (20 keV – 500 keV). PACS No.: 36.10.Dr

Evaluation of Luminescence Decay Measurements Probed on Pure and Doped Pt(IV) Hexahalogeno Complexes. II. Molecular Properties Obtained from Temperature Dependent Lifetime Curves

1997 ◽  
Vol 52 (5) ◽  
pp. 447-456
Author(s):  
Ingo Biertümpel ◽  
Hans-Herbert Schmidtke
Keyword(s):  
Excited States ◽  
Ground State ◽  
Energy Levels ◽  
Decay Rates ◽  
Rate Equations ◽  
Temperature Dependent ◽  
Lifetime Measurements ◽  
Thermally Activated ◽  
Ground State Energies ◽  
Higher Excited States

Abstract Lifetime measurements down to nearly liquid helium temperatures are used for determining energy levels and transition rates between excited levels and relaxations into the ground state. Energies are obtained from temperature dependent lifetimes by fitting experimental curves to model functions pertinent for thermally activated processes. Rates are calculated from solutions of rate equations. Similar parameters for pure and doped Pt(IV) hexahalogeno complexes indicate that excited levels largely belong to molecular units. Some of the rates between excited states are only somewhat larger than decay rates into the ground state, which is a consequence of the polyexponential decay measured also at low temperature (2 K). In the series of halogen complexes, the rates between spinorbit levels resulting from 3T1g increase from fluorine to bromine, although energy splittings become larger. Due to the decreasing population of higher excited states in this series, K^PtFö shows a tri-exponential, K2PtCl6 a bi-exponential and FoPtBr6 a mono-exponential decay. In the latter case the population density of higher excited states relaxes so fast that emission occurs primarily from the lowest excited Γ3(3T1g) level. Phase transitions and emission from chromophores on different sites can also be observed.

scholarly journals Electron Impact Excitation Cross Sections for B III

1983 ◽  
Vol 36 (5) ◽  
pp. 659
Author(s):  
PS Ganas ◽  
M Aryafar ◽  
LP Gately
Keyword(s):  
Electron Impact ◽  
Excited States ◽  
Cross Sections ◽  
Born Approximation ◽  
Oscillator Strengths ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Central Potential ◽  
Excitation Cross Sections ◽  
Generalized Oscillator

A realistic analytical central potential with two adjustable parameters is used to generate wavefunctions for the ground and excited states of doubly ionized boron. Generalized oscillator strengths and integrated cross sections from threshold up to 5 keY are calculated in the Born approximation for 2s-ns, 2s-np and 2s-nd excitations. Convenient analytic formulae for the cross sections are presented.

scholarly journals Ground State Positronium Formation Cross Sections for Scattering of Positrons from Li

1991 ◽  
Vol 44 (5) ◽  
pp. 515 ◽  
Author(s):  
KK Mukherjee ◽  
N Ranjit Singh ◽  
Keka Basu Choudhury ◽  
PS Mazumdar ◽  
S Brajamani
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Ground State ◽  
Positronium Formation ◽  
Distorted Wave ◽  
Total Cross Sections ◽  
Wave Approximation ◽  
Theoretical Predictions

Total cross sections for positronium formation in e+-Li scattering have been studied in the framework of the distorted wave approximation in the energy range 1-50 eV by taking consistent account of the effect of the target distortion. The results are compared with existing theoretical predictions.

scholarly journals Simplified DWBA for Heavy Ion Induced Transfer at High Energies

1979 ◽  
Vol 32 (3) ◽  
pp. 173 ◽  
Author(s):  
LR Dodd
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Ground State ◽  
Optical Model ◽  
Heavy Ion ◽  
Transfer Reactions ◽  
Angular Distributions ◽  
High Energies ◽  
Scattering States ◽  
Exact Calculations

The treatment of the distorted wave Born approximation (DWBA) for transfer reactions at high energies between complex nuclei due to Braun-Munzinger and Harney (1974) is simplified by introducing eikonal-like representations for the elastic scattering states. Simple expressions for the differential cross sections are derived. The model includes recoil approximately and takes into account the strong absorption of the nuclear cores. Reasonable values for the parameters of the model wavefunctions are determined by comparison with the usual optical model wavefunctions. Angular distributions calculated for the model are compared with the results of exact finite-range DWBA calculations and experimental data for transitions to the ground state and excited states of 13C in the reaction 12C(14N,13N)13C at several energies. The model reproduces the general features of the exact calculations, giving reasonable fits for the transitions to the ground state and the 1ds/2 (3�85 MeV) state. The transition to the 2S1/2 (3 �09 MeV) state appears to be anomalous as in the case of the full DWBA theory.

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.

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