Single- and multiphoton detachment of K 

Abstract

Single- and multiphoton detachment rates have been calculated for K− using the R-matrix Floquet approach. Single-photon detachment rates, obtained at a laser field peak intensity of 109 W cm−2, are discussed and compared with other theoretical work. Two-photon detachment rates at the same intensity have also been obtained, and similarities with results from earlier calculations for Li− and Na− are discussed. Three-photon rates are also presented at this laser intensity, and are compared and contrasted with those arising in the single-photon case, since both involve resonance structure with 1Po symmetry. The influence of resonances such as the 5s2 1Se doubly excited state and excitations of the residual atom are also considered.

Two- and three-photon ionization of He between 1013 and 1014 W cm−2

“…B-spline basis sets are excellently suited to be used within R-matrix theory, since they are defined on a closed interval. Although their use in R-matrix theory was pioneered about a decade ago (Decleva et al 1994, van der Hart 1997, it is only recently that B-spline basis sets are routinely employed within this theory (Zatsarinny and Froese Fischer 2000, Vinci et al 2003, McKenna and van der Hart 2003. In this investigation, we describe He within an inner region of radius 20 au, using a B-spline basis containing 32 splines defined using a mixed exponential/linear knot set.…”

“…Multiphoton detachment has been studied for F − (van der Hart 2000). The combination of R-matrix Floquet theory with B-spline basis sets and model potentials has enabled the study of quasi-two-electron systems such as K − (Vinci et al 2003) and Ca (McKenna and van der Hart 2003). Double-ionization processes have been studied for He within R-matrix Floquet theory van der Hart 2002, 2003).…”

Single- and two-photon ionization of neutral Ca

“…One approach that has successfully demonstrated its ability to do so is the R-matrix Floquet method (Burke et al 1991, Dörr et al 1992. This method, which, in principle, can be applied to any atomic system, allows multiphoton ionization to be examined for a wide range of atoms and ions (Glass and Burke 1999, van der Hart 2000, particularly permitting the role of resonances to be studied in detail.…”

Two-photon double ionization of helium

“…Recently, the B-spline-based R-matrix Floquet approach has been used to describe quasitwo-electron systems, such as K and Ca [19,20]. For theses systems, it is advantageous to employ model potentials, since these potentials greatly simplify the computational description, while retaining high levels of accuracy [21].…”