Excitation Cross Sections for Li-like Ions of Beryllium and Boron

摘要: We report on calculation of electron-impact excitation cross sections for Li-like ions boron and beryllium. The data were produced with a number modern methods in atomic collision theory, such as convergent close-coupling, K-matrix Coulomb–Born-exchange. results obtained are compared other calculations available expermental data, the recommended all transitions between terms principal quantum numbers n � 4 presented tables fitting parameters. Due to importance beryllium fusion astrophysics, collisional these elements have often been subject research, including sections. most recent compilation Be qþ B [1] was principally based R-matrix (RM) distorted-wave (DW) methods, included from ground into ¼ 2 3 excited states ions. It found later [2,3] that accuracy calculated RM DW sections, which used deriving sets boron, may be inferior recently developed close-coupling (CCC) pseudostates (RMPS). disagreement especially noticeable intermediate energy region, where coupling continuum is important, hence applicability limited. In addition, has noted above, not considered Ref. [1]. mentioned can only rarely literature, although they very important applications. This exemplified by experiment laser pumping specific levels [4], crucially affect measured light emission. Thus, it seems appropriate produce new set highaccuracy beryllium, states. non-perturbative (CC) type known provide highest among existing theoretical approaches, normally require significant computational efforts, both hardware requirements computation times. justifies development simpler faster, yet sufficiently accurate, could practical use widely tools. As highly-charged H- ions, already shown [5,6] first-order Coulomb-Bornexchange method (CBE) normalization one channel reliably applied large spectroscopic charge (Z 3). For low-charge however, interaction effects, ignored within CBE approximation, become more thus application CC approaches an accurate present paper