>>XFit Status, September 2004<<

XFIT for Windows is a suite of X-ray Absorption Fine Structure (XAFS) analysis programs for PCs using the Windows 95 operating system. The Windows version of XFIT was developed at the University of Sydney as a joint project with, and funded by, the Australian Synchrotron Research Program Inc.

It incorporates the following features:

• A graphical user interface driven averaging and spline program.
• A choice between ab initio and empirical calculations of XAFS.
• Single and multiple scattering XAFS calculated using the FEFF routines.
• Fourier filtering of both experimental and calculated XAFS.
• A generalised formalism for parameter constraints and restraints.
• Estimation of random errors by a Monte-Carlo technique.
• The ability to fit a model simultaneously to several XAFS data sets.
• The ability to fit a model with more than one absorption site.
• A user-friendly interface.

The package contains the following programs:

AVERAGE

AVERAGE reads fluorescence or transmission, single or multiple channel XAS data in a number of formats and produces an average XAS curve.

SPLINE

SPLINE is used to extract the XAFS from raw X-ray absorbance data. Live windows display the XAFS and Fourier-transformed XAFS as the spline is varied. See sample spline windows

GRAPH

GRAPH is a program for graphing the data in files produced by the XAFS analysis programs AVERAGE, SPLINE and XFIT. GRAPH can also be used to edit a file by deleting selected data points, eg for glitch removal. It can also estimate the random noise in a data curve and generate the curves required by the XFIT Monte-Carlo analysis.

PHASES

The PHASES program is used to generate the data files used by the FEFF4 theory in XFIT to calculate ab initio single-scattering XAFS. The program executes FEFF4 and renames the files generated.

XFIT

The XFIT program optimises the parameters of an atomic model with respect to the XAFS data produced by AVERAGE and SPLINE. XFIT uses FEFF4 for single scattering and FEFF6 for multiple scattering XAFS calculations. An additional option is error estimation via a Monte-Carlo analysis.

Extensive help is provided for each program. In addition a set of example data sets and calculations is provided.

How to Obtain XFIT for Windows

XFIT for Windows is available from the ASRP free of charge for Australian universities or research institutions, and at a nominal fee for overseas users. For instructions and the licence agreement necessary to obtain a copy of XFIT E-mail for details.

Document details: Original Web document. Author and contact Dr R Garrett

This page was last updated on 8 September, 2004