Isotope Shifts in Beryllium-, Boron-, Carbon-, and Nitrogen-like Ions from Relativistic Configuration Interaction Calculations

Energy levels, normal and specific mass shift parameters as well as electronic densities at the nucleus are reported for numerous states along the beryllium, boron, carbon, and nitrogen isoelectronic sequences. Combined with nuclear data, these electronic parameters can be used to determine values of level and transition isotope shifts. The calculation of the electronic parameters is done using first-order perturbation theory with relativistic configuration interaction wave functions that account for valence, core-valence and core-core correlation effects as zero-order functions. Results are compared with experimental and other theoretical values, when available.Comment: 56 pages, 1 figure, Atomic Data and Nuclear Data Tables (2014

INFLUENCE OF SOCIO-ECONOMIC FACTORS ON FARMERS’ USE OF MOBILE PHONES FOR AGRICULTURAL INFORMATION IN NIGERIA

Farmers use mobile phones to access information needed to improve their agricultural practice. However, in cases where they do maximize their mobile phone utilization, they may be hindered by some socio-economic factors which may lead to inadequate access to agricultural information. Therefore, this study investigated the influence of socio-economic factors on famers’ use of mobile phones for agricultural information in Nigeria. The research adopted a survey design. The study population was 9,650 registered farmers in Yewa South Local Government, Ogun State, Nigeria. The proportionate stratified random sampling technique was used. The instrument used was structured questionnaire. Data were collected from 363 farmers; thus the study had 93%. Data was analyzed using descriptive statistics, Regression and Multi regression analysis. Findings from this study revealed that majority of the farmers use mobile phones daily (75.5%). It was further showed that farmers use mobile phones for specific purposes such as making phone calls (mean= 3.47), and receiving text messages (mean= 2.90). The findings also revealed that farmers use mobile phones to acquire different types of Agricultural information such as fertilizer and pesticide information (mean=2.52), and market information (mean=2.31). High tariff deductions from telecommunication companies (mean=3.53) was a major constrain. Findings further revealed that family size (β= .173; P˂.05), and Farm Size (β= .168; P˂.05) had positive significant influence on farmers’ use of mobile phones for agricultural information while Age range (β= -.031; P˂.05), Gender (β= -.027; P˂.05), Marital status (β= -.18; P˂.05), Educational qualification (β= -.031; P˂.05), Years of farming (β= -.126; P˂.05), Farm income per month (β= -.021; P˂.05) had negative influence respectively. Finally, socio-economic factors jointly influenced farmers’ use of mobile phones for agricultural information (F = 3.81; R² = .58, p \u3c .05). The study concluded that, socio-economic factors collectively contribute to farmers’ use of mobile phones for agricultural information. Therefore, it is recommended that telecommunication companies in Nigeria, in conjunction with the Federal Government, should provide a low tariff plans for farmers. This would enable them to adequately utilize their mobile phones for agricultural information

Cascade emission in electron beam ion trap plasma of W25+^{25+} ion

Spectra of the W$^{25+}$ ion are studied using the collisional-radiative model (CRM) with an ensuing cascade emission. It is determined that the cascade emission boosts intensities only of a few lines in the $10 - 3$ nm range. The cascade emission is responsible for the disappearance of structure of lines at about 6 nm in the electron beam ion trap plasma. Emission band at 4.5 to 5.3 nm is also affected by the cascade emission. The strongest lines in the CRM spectrum correspond to $4d^{9} 4f^{4} \rightarrow 4f^{3}$ transitions, while $4f^{2} 5d \rightarrow 4f^{3}$ transitions arise after the cascade emission is taken into account.Comment: 16 pages including 4 figures and 3 table

Tensorial form and matrix elements of the relativistic nuclear recoil operator

Within the lowest-order relativistic approximation ($\sim v^2/c^2$) and to first order in $m_e/M$, the tensorial form of the relativistic corrections of the nuclear recoil Hamiltonian is derived, opening interesting perspectives for calculating isotope shifts in the multiconfiguration Dirac-Hartree-Fock framework. Their calculation is illustrated for selected Li-, B- and C-like ions. The present work underlines the fact that the relativistic corrections to the nuclear recoil are definitively necessary for getting reliable isotope shift values.Comment: 22 pages, no figures, submitted to J. Phys.

Theoretical studies of energy levels and transition data for Zr III

Aims. We seek to present accurate and extensive transition data for the Zr III ion. These data are useful in many astrophysical applications. Methods. We used the multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction (RCI) methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2018. The transverse-photon (Breit) interaction, vacuum polarization, and self-energy corrections are included in the RCI computations. Results. Energy spectra were calculated for the 88 lowest states in the Zr III ion. The root-mean-square deviation obtained in this study for computed energy spectra from the experimental data is 450 cm−1. Electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2) transition data, line strengths, weighted oscillator strengths, and transition rates are computed between the above states together with the corresponding lifetimes. The computed transition rates are smaller than the experimental rates and the disagreement for weaker transitions is much larger than the experimental error bars. The computed lifetimes agree with available experimental values within the experimental uncertainties

Energies and E1, M1, E2, and M2 transition rates for states of the 2s

Based on relativistic wave functions from multiconfiguration Dirac-Hartree-Fock and configuration interaction calculations, E1, M1, E2, M2 transition rates, weighted oscillator strengths, and lifetimes are evaluated for the states of the (1s2)2s22p4,2s2p5, and 2p6 configurations in all oxygen-like ions between F II and Kr XXIX. Valence and core-valence correlation effects were accounted for through single-double multireference (SD-MR) expansions to increasing sets of active orbitals. Computed energies are compared with the NIST recommended values, generally differing by less than 600 cm-1. For some spectra, significantly larger differences are found and our results are in better agreement with Edlén interpolated values. For levels where experimental lifetimes are available, the agreement is within experimental uncertainty for all but a few lowly ionized spectra. Complete Online tables of energy levels and transition data are available