Gaussian Type Orbitals basis sets for the calculation of continuum properties in molecules: the differential photoionization cross section of acetylene

By using the K-matrix technique for the continuum states that was previously employed with particularly diffuse L2 basis sets, it is shown that GTO bases are also capable of yielding accurate values for the properties belonging to the electronic continuum. The method has been tested for helium and proved of satisfactory accuracy also for the analysis of the autoionizing states. The results include the phase shifts of the continuum states of the 1Seand 1P° manifolds, the properties of the lowest resonances of these symmetries, the ground state photoionization cross section, and the S contribution to the 1s2p1P° photoionization cross section. The results obtained suggest that the proposed technique should be useful for computing molecular differential photoionization cross sections by exploiting the widely used codes that employ GTO bases. Keywords: photoionization, Gaussian basis sets, helium, autoionizing states.

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XUV Absorption Spectra of Carbon Ions

International Astronomical Union Colloquium ◽

10.1017/s0252921100107444 ◽

1988 ◽

Vol 102 ◽

pp. 71-73

Author(s):

E. Jannitti ◽

P. Nicolosi ◽

G. Tondello

Keyword(s):

Absorption Spectra ◽

Cross Section ◽

Theoretical Calculations ◽

Photoionization Cross Section ◽

Carbon Ions

AbstractThe photoabsorption spectra of the carbon ions have been obtained by using two laser-produced plasmas. The photoionization cross-section of the CV has been absolutely measured and the value at threshold, σ=(4.7±0.5) × 10−19cm2, as well as its behaviour at higher energies agrees quite well with the theoretical calculations.

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Photoionization Cross-Sections of Carbon-Like N+ Near the K-Edge (390–440 eV)

Atoms ◽

10.3390/atoms9020027 ◽

2021 ◽

Vol 9 (2) ◽

pp. 27

Author(s):

Jean-Paul Mosnier ◽

Eugene T. Kennedy ◽

Jean-Marc Bizau ◽

Denis Cubaynes ◽

Ségolène Guilbaud ◽

...

Keyword(s):

High Resolution ◽

Cross Section ◽

Cross Sections ◽

Experimental Studies ◽

Photoionization Cross Section ◽

Theoretical Work ◽

Rydberg Series ◽

R Matrix ◽

Resonance Strengths ◽

Nitrogen Ion

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398–403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415–440 eV photon region 1s⟶(1s2s22p2 4P)np and 1s⟶(1s2s22p2 2P)np resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

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