H, He-like recombination spectra VI : Quadrupole l-changing collisions

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Deliporanidou, E. and Badnell, N. R. and Storey, P J and Del Zanna, G. and Ferland, G. J. (2025) H, He-like recombination spectra VI : Quadrupole l-changing collisions. Monthly Notices of the Royal Astronomical Society. ISSN 1365-2966 (https://doi.org/10.1093/mnras/staf608)

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Abstract

We have developed a simple analytic formula that well describes quadrupole l-changing collisions of the form nl → nl′, as confirmed by comparison with numerical quantal Born calculations obtained with the program autostructure (Badnell 2011). Such formulae could easily be included in models of astrophysical plasma emission, such as the hydrogen and helium-like recombination spectra. When compared with the results of previous quantal calculations based upon an analytic solution of the time-dependent Schrödinger equation by Vrinceanu & Flannery (2001), we find relatively good agreement, with the exception of large l > n/2 transitions. We provide a tentative explanation for such discrepancies. However, we also show that the rates for quadrupole l-changing collisions are typically two orders of magnitude lower than the dipolar ones. Inclusion of the quadrupolar rates in a hydrogenic collisional-radiative model of nebular plasma shows minimal changes to the level populations, typically within 1 % in nebular conditions. Simple and complete theories are now available for l-changing collisions suitable for astrophysical applications.

ORCID iDs

Deliporanidou, E., Badnell, N. R. ORCID logoORCID: https://orcid.org/0000-0001-7418-7996, Storey, P J, Del Zanna, G. and Ferland, G. J.;
  • Item type:Article
    ID code:92591
    Dates:
    Date
    Event
    11 April 2025
    Published
    11 April 2025
    Published Online
    1 April 2025
    Accepted
    Subjects:Science > Astronomy
    Science > Physics
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:14 Apr 2025 09:29
    Last modified:15 Apr 2025 00:24
    URI:https://strathprints.strath.ac.uk/id/eprint/92591
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