Photoionization microscopy in terms of local-frame-transformation theory

Abstract

Two-photon ionization of an alkali-metal atom in the presence of a uniform electric field is investigated using a standardized form of the local frame transformation and generalized quantum defect theory. The relevant long-range quantum defect parameters in the combined Coulombic plus Stark potential are calculated with eigenchannel R-matrix theory applied in the downstream parabolic coordinate η. The present formulation permits us to express the corresponding microscopy observables through the local frame transformation, and it gives a critical test of the accuracy of the Harmin-Fano theory.

Generalized local-frame-transformation theory for excited species in external fields

“…However, Ref. [27] demonstrates that those errors are far less severe than was claimed in Ref. [26] but they do matter for high accuracy calculations.…”

“…(II) Fano-Harmin theory assumes that the smooth Coulomb Green's function expressed in spherical coordinates is approximately equal to the smooth Coulomb Green's function expressed in parabolic coordinates which in turn is equated to the smooth Coulomb-Stark Green's function in parabolic coordinates (for a detailed discussion see Ref. [27]). On the contrary, here this assumption is dropped yielding additional corrections as they are shown in the first term of Eq.…”

“…Indeed, high precision experiments on the photoabsorption spectra 7 Li in the presence of an electric field by Stevens et al [25] showed that the Fano-Harmin LFT theory [1,2] deviates from the experimental observations by several hundreds of MHz. In addition, several theoretical investigations have attempted to identify the origin of these discrepancies and check the range of validity of the LFT [26,27]. In this paper, a generalized LFT (GLFT) theory is developed based on more reliable and complete physico-mathematical grounds whose rigor allows an extension of calculations to much higher accuracy.…”

Erratum: Calculated electron dynamics in an electric field [Phys. Rev. A56, 278 (1997)]

“…IIIA of Ref. [1]. This misclassification of the matrix S does not affect the correctness of any of the equations or results of our work.…”

Reply to “Comment on ‘Test of the Stark-effect theory using photoionization microscopy’ ”

“…Rather, we tried to caution the AMO community about limitations and inaccuracies of this theory which were first noticed long before us by Stevens et al [4]. In this Reply to the Comment [5], we will first point out the fundamental reasons for these inaccuracies. Then we will respond to the critique presented in the Comment.…”