Superconducting high-resolution X-ray detectors for metalloprotein L-edge spectroscopy

S. Friedrich, L. J. Hiller, Matthias Frank, J. B. Le Grand, C. A. Mears, B. Nideröst, S. E. Labov, A. T. Barfknecht, M. LeGros, S. P. Cramer

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Superconducting tunnel junctions (STJs) can be used as high-resolution energy-dispersive X-ray detectors. STJ detectors are based on the measurement of an increased tunneling current from excess charge carriers that are excited above the superconducting energy gap by the absorption of an X-ray. Nb-based STJ detectors have a theoretical energy resolution limit below 5 eV FWHM for X-ray energies below 1 keV at count rates up to 10 000 counts/s. We have developed Nb-Al-AlOx-Al-Nb X-ray detectors and operated them in a cryostat below 0.4 K in synchrotron experiments. Their resolution varies between 4.6 and 8.9 eV FWHM for X-ray energies between 0.2 and 1 keV. We present fluorescence spectra of metalloproteins and discuss the potential of STJ detectors for fluorescence-detected L-edge absorption spectroscopy of dilute samples.

Original languageEnglish (US)
Pages (from-to)891-896
Number of pages6
JournalJournal of Electron Spectroscopy and Related Phenomena
StatePublished - Dec 1 1999
Externally publishedYes


  • Cryogenic X-ray detectors
  • L-edge absorption spectroscopy
  • Superconducting tunnel junctions

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Radiation
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry


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