STUDIES OF PHOTOIONIZATION PROCESSES OF NITROGEN-LIKE O+ION USINGTHE SCREENING CONSTANT BY UNIT NUCLEAR CHARGEMETHOD

In this present work, we have calculated the energies positions of the 2s22p2(1D)nd2P, 2s22p2(1D)nd2S, 2s22p2(1D)ns 2D, 2s22p2(1S)nd2D and 2s2p3(3P)np2D Rydberg series in the photoionization spectra from the 2P° metastable state of the O+ ion. Calculations were performed up to n = 40 applyingthe Screening Constant by Unit Nuclear Charge (SCUNC) via its semi empirical formalism. The quantum defect and the effective charge are also calculated.The results agree within 98% to Aguilars experimental data, and with Sows theoretical results to within 99%. These data can be a useful guideline for future experimental and theoretical studies.

Rydberg series of dark excitons and the conduction band spin-orbit splitting in monolayer WSe2

Strong Coulomb correlations together with multi-valley electronic bands in the presence of spin-orbit interaction are at the heart of studies of the rich physics of excitons in monolayers of transition metal dichalcogenides (TMD). Those archetypes of two-dimensional systems promise a design of new optoelectronic devices. In intrinsic TMD monolayers the basic, intravalley excitons, are formed by a hole from the top of the valence band and an electron either from the lower or upper spin-orbit-split conduction band subbands: one of these excitons is optically active, the second one is dark, although possibly observed under special conditions. Here we demonstrate the s-series of Rydberg dark exciton states in tungsten diselenide monolayer, which appears in addition to a conventional bright exciton series in photoluminescence spectra measured in high in-plane magnetic fields. The comparison of energy ladders of bright and dark Rydberg excitons is shown to be a method to experimentally evaluate one of the missing band parameters in TMD monolayers: the amplitude of the spin-orbit splitting of the conduction band.

SCREENING CONSTANT BY UNIT NUCLEAR CHARGE CALCULATIONS OF THE RYDBERG SERIES FROM METASTABLE STATE OF CALCIUM ION

We report in this paper energy positions of Rydberg series from metastable state of Ca3+ ion.. Calculations are performed up to n = 20 using the Screening Constant by Unit Nuclear Charge (SCUNC). The present results compared wellwith the experimental data of Ghassan A Alna’washi which are the only available values.The accurate data presented in this work may be a useful guideline for future experimental and other theoretical studies.

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

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.

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

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 eV - 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 eV - 440 eV photon region 1s⟶1s2s22p2 4Pnp and 1s⟶1s2s22p2 2Pnp 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.