Photoionization Processes of the Single-Ionized Boron

The relativistic calculations of the cross-section , the angular-distribution parameter , and spin-polarization parameters of photoelectrons using the multiconfiguration relativistic random-phase approximation theory for the photoionization of the ion are presented. Precise energies and widths of all five Rydberg series of doublyexcited states , , , , and are determined. Our predictions are in very close agreement with experiments and are consistent with other calculations. 1. Introduction Experimental and theoretical studies of photoionization processes are of fundamental importance because they have greatly increased the understanding of the responses of atoms or ions to electromagnetic radiations. In recent years, the development of merged ion-photon beams and third-generation synchrotron radiation facilities provides sufficiently high density of target ions and the required incident photon flux. These high-resolution measurements attributed to rapidly evolving experimental techniques enhanced the ability to study the photoionization of atomic systems along isoelectronic, isonuclear, and isoionic series. Divalence atomic systems such as the Be-isoelectronic sequence are attractive candidates for the systematic studies of the photoionization processes because of their relatively simple quasi-two-electron structure. In these atomic systems, two loosely bound electrons in the L-shell are well separated from the other two tightly bound K-shell electrons. They are suitable for comprehensive studies of electron-correlation and relativistic effects in photoionization processes. In addition, many works have shown that relativistic effects play an important role in the photoionization of small atoms, such as Be [1–4], Ne [5], and Mg [6–8]. Therefore, it is worthwhile to investigate the interplay between electron-correlation and relativistic effects on the photoionization of atoms or ions with a low nuclear charge. Considerable theoretical and experimental efforts have been made recently to investigate the photoionization of the ion. Among the theoretical results are the R-matrix calculations of Tully et al. [9, 10], the B-spline-based configuration-interaction approach of Chang and Zhu [11], and the noniterative eigenchannel R-matrix method of Kim and Manson [12]. On the experimental side, the absorption spectrum of has been measured by Esteva [13]. Jannitti et al. [14] investigated the absorption spectrum of for photon energies between 400 and 1700？？ by using two-laser produced plasma. Recently, a good agreement between theory and experiment for the