Photoionization and electron-ion recombination of Ti I

作者：Nahar Sultana N^*

来源：New Astronomy, 2016, 46: 1-8.

DOI：10.1016/j.newast.2015.11.003

• Photoionization and electron ion recombination
• State-specific rates of Ti I
• Unified method
• Recombination spectrum

Study of the inverse processes of photoionization and electron-ion recombination of (Ti I + h nu reversible arrow Ti II + e) using the unified method is reported. The method, based on close coupling (CC) approximation and R-matrix method, subsumes both the radiative recombination (RR) and dielectronic recombination (DR) in a unified manner and provides state-specific and total electron-ion recombination rate coefficients which are self consistent with the state-specific photoionization cross sections. The present results include state-specific electron-ion recombination rates (alpha(RC)(i) and partial photoionization cross sections (sigma(PI)(i)) leaving the ion in the ground state of 813 bound states with n <= 10 and l <= 9 of Ti I. Various features of state-specific and total electron-ion recombination with temperature, and the corresponding photoionization cross sections with energies are discussed with illustrations. Due to closely lying excited states near the ground state of the core, photoionization cross sections show presence of narrow Rydberg resonances in low energy region near the ionization threshold. Many excited states also show broad and enhanced Seaton resonances due to PEC (photo-excitation-of-core) which contribute to the high temperature recombination. The total recombination rate coefficient is found to show a low hump around temperature 280 K and a high dielectronic recombination peak at temperature 25,000 K. Total spectrum of recombination cross sections and rates with photoelectron energy are also presented for experimental observation. Calculations were carried out using a CC wave function expansion of 36 states of the core ion Ti II. The large set of data for recombination rates and partial photoionization cross sections with resonances should provide a complete and accurate modelings of plasmas.

• 出版日期2016-7