Abstract
Single electron hydrogen or hydrogenic ions have analytical forms to evaluate the atomic parameters for the inverse processes of photoionization and electron-ion recombination (H I + hν↔ H II + e) where H is hydrogen. Studies of these processes have continued until the present day (i) as the computations are restricted to lower principle quantum number n and (ii) to improve the accuracy. The analytical expressions have many terms and there are numerical instabilities arising from cancellations of terms. Strategies for fast convergence of contributions were developed but precise computations are still limited to lower n. This report gives a brief review of the earlier precise methodologies for hydrogen, and presents numerical tables of photoionization cross sections (σPI), and electron-ion recombination rate coefficients (αRC) obtained from recombination cross sections (σRC) for all n values going to a very high value of 800. σPI was obtained using the precise formalism of Burgess and Seaton, and Burgess. αRC was obtained through a finite integration that converge recombination exactly as implemented in the unified method of recombination of Nahar and Pradhan. Since the total electron-ion recombination includes all levels for n = 1–∞, the total asymptotic contribution of n = 801–∞, called the top-up, is obtained through a n−3 formula. A FORTRAN program “hpxrrc.f” is provided to compute photoionization cross sections, recombination cross sections and rate coefficients for any nl. The results on hydrogen atom can be used to obtain those for any hydrogenic ion of charge z through z-scaling relations provided in the theory section. The present results are of high precision and complete for astrophysical modelings.
Highlights
Photoionization and electron-ion recombination are inverse processes which can be described asX+z + hν X+z+1 + e (1)where a hydrogenic ion X ion of charge +z is being ionized by a photon of energy hν. e is the ejected photoelectron or recombining ion
Astrophysical modeling for spectral analysis for abundances, ionization fractions, diagnostics for the physical and chemical conditions, plasma opacity, etc. require electron-ion recombination rate coefficients and photoionization cross sections, if the plasma is around or near a radiative source, such as a star where plasma is being ionized by photons
The present work aims to present state-specific photoionization cross sections, electronion recombination rate coefficient of hydrogen ion for a very large number of n going up to 800, total recombination cross sections, and relevant codes that can be incorporated to astrophysical modelings and extend to hydrogenic ions of any charge z
Summary
Photoionization and electron-ion recombination are inverse processes which can be described as. Require electron-ion recombination rate coefficients and photoionization cross sections, if the plasma is around or near a radiative source, such as a star where plasma is being ionized by photons. The solution for photoionization cross sections (σPI) and recombination rate coefficients (αRC) for hydrogenic ions can be expressed exactly. For higher accuracy with faster approaches for photoionization cross sections and electron-ion recombination rates of hydrogenic ions, the investigation has continued. The present work aims to present state-specific photoionization cross sections, electronion recombination rate coefficient of hydrogen ion for a very large number of n going up to 800, total recombination cross sections, and relevant codes that can be incorporated to astrophysical modelings and extend to hydrogenic ions of any charge z
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