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What is SIXPACK?

SIXPACK is Sam's Interface for XAS Package, a software
package for x-ray absorption spectroscopy data

The interface builds on Matt Newville's IFEFFIT engine

It contains the following modules:
  • Averaging, calibrating, and deadtime correcting raw data

  • Background subtraction of data to create normalized mu(E) and chi(k) functions

  • A FEFF periodic table interface to create single scattering phase and amplitude paths - Now compatible with FEFF6 through FEFF8.

  • A GUI for the fitting of experimental EXAFS to theoretically derived phase and amplitude files

  • A GUI for linear combination fitting of EXAFS or XANES to experimentally obtained reference spectra

  • A principal component analysis routine that decomposes data into a set of orthogonal components.  Also features a target transformation feature to check if potential reference spectra are in the component space defined by the samples.


The SamView module is a general purpose XAS data preprocessing program.  It reads raw data collected from a beamline and allows the user to view raw data, average scans, calibrate energy, and perform deadtime corrections for solid state detectors.

Data formats:

  • SSRL XAScollect binaries

  • SSRL XAScollect ASCII files

  • X-ray Data Interchange (XDI) format

  • DND-CAT quick-scanning XAS binary files

  • DND-CAT ASCII files from step XAS scans

  • DND-CAT ASCII files from multi-element detectors

  • GSE-CARS single and multi-element detectors

  • PNC-CAT simple format

  • SOLEIL NXS data formats

  • SRC multi-element detector format

  • ALS beamline 10.3.2

  • NSLS beamlines X-11A, X-23A2 and X-23B

  • NSLS BSIF binary format for X26A 1-D data

  • Generic ASCII format for other formats


Future ability to include other formats is planned, including possible plug-in type support.  A generic ASCII file loader is provided to accommodate other file formats.  The background subtraction module adds the ability to perform the subtraction of gaussian type pre-edge removal to the standard complements of background removal and spline fitting.  The gaussian method is a useful approach to remove the scattering contributions of low concentration samples collected with solid-state detectors.  A special feature of the XANES fitting routine is the ability to make corrections for self-absorbance to spectra obtained using fluorescence yield detectors (i.e. Lytle cells or Ge solid state arrays).  The program is still in its mid-life stage of development, but all questions and particularly comments for improvement are welcomed.


Coming Soon:  Tutorials!  New documentation to reflect recent improvements (badly needed)!

How to Cite

Webb S.M. (2005) SIXPACK: A graphical user interface for XAS analysis using IFEFFIT. Physica Scripta T115, 1011-1014.


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