{
  "abstract": "Electron paramagnetic resonance (EPR) spectroscopy is a widely used technique for the characterization of paramagnetic centers across a wide range of disciplines. Yet, the detection limits of conventional 3D microwave resonators hinder the application of EPR to nanoscale and magnetically dilute thin films relevant to quantum, catalytic and biological devices. Here we show that high temperature superconducting spiral microresonators fabricated from YBa2Cu3O7-x enable pulse EPR measurements on diverse thin films with a sensitivity improvement of two to three orders of magnitude over commercial resonators. Templated 50 nm films of copper phthalocyanine (CuPc) diluted in metal-free phthalocyanine (H2Pc) deposited onto the microresonator were detectable in echo-detected EPR field sweeps with the templating effect clearly visible from narrowing of the spectrum compared to powder samples. The number of Cu(II) spins present in a single thin film of CuPc on a microresonator with 400 μm diameter was ~1011, as determined by measurement of coherence memory times (Tm) and longitudinal (T1) spin relaxation times. The Carr-Purcell-Meiboom-Gill (CPMG) sequence was also employed, enabling improved SNR by averaging multiple echoes obtained from echo trains. To demonstrate biological application, Cu,Zn superoxide dismutase (SOD) was incorporated into trehalose films of ~3.7 μm average thickness, containing ~1012 Cu(II) centers. Hyperfine spectroscopy (ESEEM and HYSCORE) was successfully performed on the SOD films, producing spectra that match conventional measurements taken with ~104 times more enzyme. These results establish superconducting microresonators as a versatile high-sensitivity platform for pulse EPR of ultrathin and volume-limited films. The transformation of EPR from a ‘bulk’ to a ‘surface’ technique will facilitate the study of quantum materials, catalytic interfaces and bio-integrated devices.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Chemistry and Centre for Pulse EPR",
    "Imperial College London",
    "Department of Materials and London Centre for Nanotechnology",
    "London Centre for Nanotechnology",
    "University College London",
    "Faculty of Physics",
    "Vilnius University"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 10,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Blaise L. Geoghegan"
    },
    {
      "affs": [
        2,
        1
      ],
      "name": "Emma Bryan"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Yunfei Dang"
    },
    {
      "affs": [
        3,
        4
      ],
      "name": "Jean-Baptiste Verstraete"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Alberto Collauto"
    },
    {
      "affs": [
        5,
        6
      ],
      "name": "Gediminas Usevičius"
    },
    {
      "affs": [
        5,
        6
      ],
      "name": "Mantas Šimėnas"
    },
    {
      "affs": [
        2,
        1
      ],
      "name": "Sandrine Heutz"
    },
    {
      "affs": [
        3,
        4
      ],
      "name": "John J. L. Morton"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Maxie M. Roessler",
      "orcid": "0000-0002-5291-4328"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dnhxngv6pd7y2.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15008536/v1",
  "fulltext_url": null,
  "id": "dnhxngv6pd7y2",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008536/v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1304|Electron Spin Resonance Studies"
    ]
  ],
  "openalex": "W7211996944",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15008536/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-09",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/dnhxngv6pd7y2.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:19Z",
      "native_id": "10.26434/chemrxiv.15008536",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008536/v1"
    }
  ],
  "subjects": [
    {
      "field": "biochemistry",
      "origin": "openalex:1304|Electron Spin Resonance Studies",
      "subfield": "biophysics"
    }
  ],
  "title": "From Materials to Metalloenzymes: Superconducting Microresonators for Characterization of Thin Films",
  "title_text": "From Materials to Metalloenzymes: Superconducting Microresonators for Characterization of Thin Films",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:19Z",
  "url": "https://research.draconitic.com/paper/dnhxngv6pd7y2",
  "venue": "ChemRxiv",
  "versions": []
}