{
  "abstract": "X-ray absorption spectroscopy (XAS) and resonant-Auger spectroscopy probe different stages of core-hole excitation and decay, but distinct spectra need not provide independent information about decay parameters. We quantify their complementarity for the $Ar^+$ $2p\\to3d$ manifold using state-resolved atomic calculations and a two-parameter Fisher-information model. A common scale of primary autoionization rates $s_Γ$ and a selective spectator-$pp$ rescaling $η_{pp}$ both alter XAS linewidths. Their spectral responses are nearly collinear because the spectator-$pp$ fraction varies weakly among populated intermediate states. We compare XAS with an effective, scan-integrated, normalized Auger spectrum defined on a final-state-energy coordinate, with fixed excitation weights and final-state widths. Within this reduced observable, the common rate scale cancels from the normalized branching fractions, while $η_{pp}$ redistributes intensity among ionic final states. This cancellation is a property of the adopted model, not of photon-energy-resolved resonant-Auger spectroscopy generally. Under the reference count and resolution assumptions, XAS alone yields a Cramér-Rao lower bound (CRLB) corresponding to a 1.20% local fractional standard uncertainty in the excitation-weighted total natural width; adding Auger reduces this uncertainty by only 0.70%. In contrast, the uncertainty in the spectator-$pp$ branching fraction falls by 99.19%, with similarly large gains for partial-rate scales. A generalized Fisher comparison gives a 123.5-fold improvement on the standard-deviation scale along the most enhanced information mode. Thus, the principal benefit of the complementary Auger observable is to resolve a nearly degenerate decay-channel decomposition rather than substantially refine the total natural width.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.26234",
  "author_total": 1,
  "authors": [
    {
      "name": "Hadeel Hamid Saud"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/d4gw1g5pm3nsz.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.26234",
  "fulltext_url": null,
  "id": "d4gw1g5pm3nsz",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.26234",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.atom-ph"
    ],
    [
      "openalex",
      "3108|X-ray Spectroscopy and Fluorescence Analysis"
    ]
  ],
  "openalex": "W7223055583",
  "pdf_url": "https://arxiv.org/pdf/2610.26234",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-19",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/d4gw1g5pm3nsz.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:30:52Z",
      "native_id": "2610.26234",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.26234"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.atom-ph",
      "subfield": "amo"
    }
  ],
  "title": "How Much Does Auger Spectroscopy Add to XAS? A Fisher-information Analysis of Core-Hole Dynamics in $Ar^+$",
  "title_text": "How Much Does Auger Spectroscopy Add to XAS? A Fisher-information Analysis of Core-Hole Dynamics in Ar^+",
  "type": "preprint",
  "updated_at": "2026-10-30T12:33:41Z",
  "url": "https://research.draconitic.com/paper/d4gw1g5pm3nsz",
  "venue": "arXiv",
  "versions": []
}