Proton excitation rate coefficients and cross sections among the fine-structure levels of the (2s2p)3P state in Be-like ions

1987 ◽  
Vol 37 (3) ◽  
pp. 441-453 ◽  
Author(s):  
J.G. Doyle
Keyword(s):  
Fine Structure ◽  
Cross Sections ◽  
Rate Coefficients ◽  
Excitation Rate

scholarly journals Rotational relaxation of HCO+ and DCO+ by collision with H2

2020 ◽  
Vol 497 (4) ◽  
pp. 4276-4281 ◽  
Author(s):  
Otoniel Denis-Alpizar ◽  
Thierry Stoecklin ◽  
Anne Dutrey ◽  
Stéphane Guilloteau
Keyword(s):  
Cross Sections ◽  
Rate Coefficients ◽  
Local Thermal Equilibrium ◽  
Rotational Relaxation ◽  
Close Coupling ◽  
Excitation Rate ◽  
Rotational States ◽  
Non Local ◽  
The Difference ◽  
Isotopic Effects

ABSTRACT The HCO+ and DCO+ molecules are commonly used as tracers in the interstellar medium. Therefore, accurate rotational rate coefficients of these systems with He and H2 are crucial in non-local thermal equilibrium models. We determine in this work the rotational de-excitation rate coefficients of HCO+ in collision with both para- and ortho-H2, and also analyse the isotopic effects by studying the case of DCO+. A new four-dimensional potential energy surface from ab initio calculations was developed for the HCO+–H2 system, and adapted to the DCO+–H2 case. These surfaces are then employed in close-coupling calculations to determine the rotational de-excitation cross-sections and rate coefficients for the lower rotational states of HCO+ and DCO+. The new rate coefficients for HCO+ + para-H2 were compared with the available data, and a set of rate coefficients for HCO+ + ortho-H2 is also reported. The difference between the collision rates with ortho- and para-H2 is found to be small. These calculations confirm that the use of the rate coefficients for HCO+ + para-H2 for estimating those for HCO+ + ortho-H2 as well as for DCO+ + para-H2 is a good approximation.

Excitation Rate Coefficients for Fine‐Structure Transitions in O iii

1999 ◽  
Vol 123 (1) ◽  
pp. 311-349 ◽  
Author(s):  
Kanti M. Aggarwal ◽  
Francis P. Keenan
Keyword(s):  
Fine Structure ◽  
Rate Coefficients ◽  
Excitation Rate

The Relative Intensities of Lines From Bel-Like Ions in the Solar Spectrum

1971 ◽  
Vol 2 ◽  
pp. 519-526 ◽  
Author(s):  
Carole Jordan
Keyword(s):  
Cross Sections ◽  
Solar Spectrum ◽  
Rate Coefficients ◽  
Private Communication ◽  
Intensity Data ◽  
Excitation Rate ◽  
Excitation Cross Sections ◽  
Intensity Ratios ◽  
Intercombination Line

The permitted transitions 2s21S-2s2p1P and 2s2p3P-2p23P in the Bel-like ions CIII, NIV and OV have been observed for some years in the solar spectrum (Hall et al., 1963). Recently, intensity data have also been obtained for the intercombination line 2s21S-2s2p3P1 in these ions (Burton et al., 1970). A large number of excitation rate coefficients are needed before the intensity ratios of these transitions can be computed and compared with those observed. These excitation cross-sections are now becoming available (Osterbrock, 1970; Eissner, private communication), and the present paper gives the results of an analysis of the intensity data. Figure 1 shows a partial term scheme for the Bei-like ions and the observed transitions.

scholarly journals Excitations of the nS States of Atomic Hydrogen by Electron Impact, Excitation Rate Coefficients, and Phase Shifts: Comparison with Positron Impact Excitation

Atoms ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Anand K. Bhatia
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Atomic Hydrogen ◽  
Phase Shifts ◽  
Impact Excitation ◽  
Rate Coefficients ◽  
Orbital Method ◽  
Positron Impact ◽  
Excitation Rate ◽  
Excitation Cross Sections

The excitation cross-sections of the nS states of atomic hydrogen, n = 2 to 6, by electron impact on the ground state of atomic hydrogen were calculated using the variational polarized-orbital method at various incident electron energies in the range 10 to 122 eV. Converged excitation cross-sections were obtained using sixteen partial waves (L = 0 to 15). Excitation cross-sections to 2S state, calculated earlier, were calculated at higher energies than before. Results obtained using the hybrid theory (variational polarized orbital method) are compared to those obtained using other approaches such as the Born–Oppenheimer, close-coupling, R-matrix, and complex-exterior scaling methods using only the spherical symmetric wave functions. Phase shifts and elastic cross-sections are given at various energies and angular momenta. Excitation rate coefficients were calculated at various electron temperatures, which are required for plasma diagnostics in solar and astrophysics to infer plasma parameters. Excitation cross-sections are compared with those obtained by positron impact excitation.

scholarly journals Recent Advances in Atomic Calculations and Experiments of Interest in the Study of Planetary Nebulae

1983 ◽  
Vol 103 ◽  
pp. 143-172 ◽  
Author(s):  
C. Mendoza
Keyword(s):  
Cross Sections ◽  
Transition Probabilities ◽  
Planetary Nebulae ◽  
Electron Excitation ◽  
Rate Coefficients ◽  
Excitation Rate ◽  
Recent Advances

Recent advances in the calculation and measurement of transition probabilities, electron excitation rate coefficients and photoionization cross sections relevant to the study of planetary nebulae are discussed. A compilation of these parameters is also presented.

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