Theoretical studies of cross sections and photoelectron angular distributions in the valence photoionization of molecular oxygen

2002 ◽  
Vol 116 (20) ◽  
pp. 8863-8875 ◽  
Author(s):  
Ping Lin ◽  
Robert R. Lucchese
Keyword(s):  
Molecular Oxygen ◽  
Cross Sections ◽  
Angular Distributions ◽  
Theoretical Studies ◽  
Photoelectron Angular Distributions

The (K−,π−) and (π+, K+) Reactions and Λ-Hypernuclear Polarization

1994 ◽  
Vol 117 ◽  
pp. 17-53 ◽  
Author(s):  
K. Itonaga ◽  
T. Motoba ◽  
M. Sotona
Keyword(s):  
Experimental Data ◽  
Excited States ◽  
Cross Sections ◽  
Ground State ◽  
Weak Decay ◽  
Angular Distributions ◽  
Theoretical Studies ◽  
Excitation Functions ◽  
Unnatural Parity ◽  
Natural Parity

The theoretical studies of (K−, π−) and (π+, K+) reactions on p-shell targets are presented in the DWIA framework with use of the elementary spin-nonflip and spin-flip amplitudes. Calculations can explain the available experimental data of excitation functions and angular distributions of the (K−, π−) reactions at pK−=800 MeV/c and the (π+, K+) reactions at pπ+ = 1.04 GeV/c. Characteristic and distinguished features of the excitation functions and cross sections are exhibited. Especially it is demonstrated that the (K−, π−) reactions at pK−=1.1 GeV/c and 1.5 GeV/c can excite the unnatural parity states with comparable strength to the natural parity ones. Further interesting is that the (π+, K+) and (K−, π−) reactions with ∼1 GeV/c incident beams can be shown to produce very large polarizations of the produced hypernuclear states. Taking the subsequent deexcitation processes of the excited states into account, we have evaluated the hypernuclear polarization and Λ-spin polarization of the ground state and/or the ground-doublet states at the hypernuclear weak-decay stage, which would play a role in the hypernuclear coincidence experiment.

scholarly journals Photoelectron Angular Distributions of Nonresonant Two-Photon Atomic Ionization Near Nonlinear Cooper Minima

Atoms ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 54
Author(s):  
Jiri Hofbrucker ◽  
Latifeh Eiri ◽  
Andrey V. Volotka ◽  
Stephan Fritzsche
Keyword(s):  
Cross Sections ◽  
Incident Light ◽  
Angular Distributions ◽  
Two Photon ◽  
Atomic Ionization ◽  
Independent Particle ◽  
Photon Ionization ◽  
Ionization Cross Sections ◽  
Photoelectron Angular Distributions ◽  
Asymmetry Parameters

Photoelectron angular distributions of the two-photon ionization of neutral atoms are theoretically investigated. Numerical calculations of two-photon ionization cross sections and asymmetry parameters are carried out within the independent-particle approximation and relativistic second-order perturbation theory. The dependence of the asymmetry parameters on the polarization and energy of the incident light as well as on the angular momentum properties of the ionized electron are investigated. While dynamic variations of the angular distributions at photon energies near intermediate level resonances are expected, we demonstrate that equally strong variations occur near the nonlinear Cooper minimum. The described phenomena is demonstrated on the example of two-photon ionization of magnesium atom.

Vibrationally resolved K-shell photoionization cross sections of methane

Open Physics ◽  
2013 ◽  
Vol 11 (9) ◽  
Author(s):  
Etienne Plésiat ◽  
Piero Decleva ◽  
Fernando Martín
Keyword(s):  
Cross Sections ◽  
Density Functional ◽  
Dft Method ◽  
Chem Phys ◽  
Angular Distributions ◽  
Functional Theory ◽  
The Rich ◽  
Photoelectron Angular Distributions ◽  
Molecular Frame ◽  
Good Agreement

AbstractWe use an extension of the static-exchange density functional theory (DFT) method, previously reported in [E. Plésiat et al., Phys. Rev. A 2, 023409 (2012), E. Plésiat, P. Decleva, F. Martín, Phys. Chem. Chem. Phys. 31, 10853 (2012)], to evaluate vibrationally resolved (total and angular) K-shell photoelectron cross sections of methane. The calculated cross sections are in very good agreement with the existing experimental measurements at low photoelectron energies. We show that, in contrast with the rich interference patterns previously observed in molecular frame C(1s) photoelectron angular distributions of methane at both low and high photoelectron energy, no interference effects are observed in the calculated β parameters, even at high photon energies.

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