CHARACTERISTIC SPECTRAL FEATURES IN PHOTOIONIZATION OF Ca III

Characteristic spectral features in photoionization of Ca III, (Ca~III + h$\nu$ $\rightarrow$ Ca~IV + e), are studied in the relativistic Breit-Pauli R-matrix (BPRM) approximation. A large close-coupling wave function expansion of Ca III which includes core ion excitation of 54 levels belonging to configurations $3s^23p^5$, $3s3p^6$, $3s^23p^43d$, $3s^23p^44s$, $3s^23p^44p$, $3s^22p^44d$ of Ca IV is employed. Excited configurations with n=4 orbitals enable study of high energy features in photoionization and to achieve convergence of resonances. Calculations include 14 terms for the R-matrix basis set for the orbitals inside the R-matrix sphere and 69 bound channel configurations of Ca III. We find a total of 473 bound fine structure levels of Ca III with 0 $\leq J \leq$10 of even and odd parities and $n\leq$10 and $l\leq$9. Spectroscopic identifications of the bound levels have been carried out using quantum defects, channel percentage contributions, and angular momenta algebra. Computations for photoionization of all bound levels are complete and under analysis. Fine energy mesh has been used to reveal the characteristic resonant spectral features in photoionization of various types of fine structure levels, such as, ground level, equivalent electron levels, low energy and high energy excited levels.Impact of Seaton resonances, particularly in the high energy region will be investigated. Findings of the study will be presented at the conference.