Superconducting High-Resolution X-Ray Spectrometers For Chemical State Analysis Of Dilute Samples

Journal Article · Wed May 12 04:00:00 EDT 2004 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.1757962· OSTI ID:20653123

Friedrich, Stephan; Drury, Owen B ^[1]; Funk, Tobias; Sherrell, Darren; Yachandra, Vittal K ^[2]; Labov, Simon E ^[1]; Cramer, Stephen P ^[3]

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1. Advanced Detector Group, Lawrence Livermore National Laboratory, L-270, Livermore, CA 94550 (United States)
2. Physics Biosciences Division, Lawrence Berkeley National Laboratory, MS 6-2100, Berkeley, CA 94720 (United States)
3. Department of Applied Science, University of California, Davis, CA, 95616 (United States)

Cryogenic X-ray spectrometers operating at temperatures below 1 K combine high energy resolution with broadband efficiency for X-ray energies up to 10 keV. They offer advantages for chemical state analysis of dilute samples by fluorescence-detected X-ray absorption spectroscopy (XAS) in cases where conventional Ge or Si(Li) detectors lack energy resolution and grating spectrometers lack detection efficiency. We are developing soft X-ray spectrometers based on superconducting Nb-Al-AlOx-Al-Nb tunnel junction (STJ) technology. X-rays absorbed in one of the superconducting electrodes generate excess charge carriers in proportion to their energy, thereby producing a measurable temporary increase in tunneling current. For STJ operation at the synchrotron, we have designed a two-stage adiabatic demagnetization refrigerator (ADR) with a cold finger that holds a 3 x 3 array of STJs inside the UHV sample chamber at a temperature of {approx}0.1 K within {approx}15 mm of a room temperature sample. Our STJ spectrometer can have an energy resolution below 10 eV FWHM for X-ray energies up to 1 keV, and has total count rate capabilities above 100,000 counts/s. We will describe detector performance in synchrotron-based X-ray fluorescence experiments and demonstrate its use for XAS on a dilute metal site in a metalloprotein.

• OSTI ID: 20653123
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 705; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ABSORPTION SPECTROSCOPY
ADIABATIC DEMAGNETIZATION
ALUMINIUM OXIDES
CHARGE CARRIERS
CHEMICAL STATE
COUNTING RATES
EFFICIENCY
ELECTRODES
ENERGY RESOLUTION
EV RANGE 01-10
FLUORESCENCE
FLUORESCENCE SPECTROSCOPY
KEV RANGE 01-10
LI-DRIFTED SI DETECTORS
NIOBIUM COMPOUNDS
PERFORMANCE
REFRIGERATORS
SOFT X RADIATION
SUPERCONDUCTING DEVICES
SUPERCONDUCTING JUNCTIONS
SYNCHROTRON RADIATION
SYNCHROTRONS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0273-0400 K
TUNNEL EFFECT
X-RAY SPECTRA
X-RAY SPECTROMETERS
X-RAY SPECTROSCOPY