Before Starting - Some Quick Queries Answered

• Data file formats supported by XFIT/Koalariet
• Where to get the example data and project files used in this tutorial
• No zero counts in the data please!
• How do I get the Options menu box back?
• Where is the File Print command?/How do I Print and get Publication Quality ASCII Column Output?
• How do I include individual peak profiles for Publication Quality ASCII Column Output
• How do Output publication ASCII Column quality plotable data on multiple refinements in a project file simultaneously?
• How do I open mutiple data files?
• How do I see all the data files in different windows?
• How do I just view a subset of the files I have opened?
• How do zoom/unzoom in xfitview?
• How do I view all the displayed data (on different Windows) but in the same X axis.
• How do I get back to seeing all the files in a single window?
• How come when I initially insert peaks - they don't fit at all? Warning, fundamental parameters is the default peak profile when starting XFIT (not Pseudo Voight or Split Pearson VII)!
• How do I Insert/Delete Peaks?
• I only see peaks on the screen labelled with 2-theta positions, how do I also toggle FWHM, Shape and Area?
• How to I get back in peak insert/delete mode again?
• How do I get back into zooming with the mouse mode?
• Why can't I see any numeric peaks labels on the screen?
• Be extra careful when using Split Pearson Peaks.
• How do I start a refinement?
• Why is the peak label I see to the left of the screen when I am refining/fitting peaks?
• Using Excel or a spread sheet to reformat the resulting peak profile data.

Elementary Peak Fitting - Relatively Simple/Contrived Examples

• Fitting symmetrical Lab XRD peaks with alpha-1/alpha-2 type emmission profiles/doublets using a Pseudo Voight profile. (Y2O3 on a Philips powder XRD)

• Fitting symmetrical singlet peaks (Single Wavelength XRD, synchtrotron, neutron, energy dispersive, etc) (Silicon Powder on Daresbury beamline 2.3) using a Pseudo Voight profile.

• Fitting Assymmetric peaks using a Split Pearson 7 (PVII) function on laboratory XRD pattern (Y2O3 on a Philips powder XRD).

• Fitting symmetrical Lab XRD peaks with alpha-1/alpha-2 type emmission profiles/doublets as singlets.

• Fitting Lab XRD data using Fundamental Parameters Approach - models diffractometer geometry which also give crystallite size and strain, and uses far fewer parameters.

Modelling Energy Dispersive Diffraction Data

(Some of this can be applied to generic Diffraction Data)

• Tricks Fitting Noisy Data with Broad Peaks (and Nasty Backgrounds)
  • When peaks are merging significantly into the background - Try fixing all peaks to be 100% Gaussian.
  • When getting into false minima, could try constraining peak widths to be the identical (best done over short ranges).
  • Rebin the raw data into fewer data points (statistically valid and speeds up the data analysis) (i.e., 4000 data points into 1000 data points)
  • Define the diffraction pattern / spectrum into sub-ranges that can be fitted in a convenient fashion.

Some More Technical Questions Answered

• Saving work as a XFIT project file - File, Save Project As menu.
• Retrieving previous work via the File, Load Project menu.
• Applying the fit parameters and defaults from a project file onto a new dataset:
  • Replacing a data file in a project with a new file but using the old files fit parameters.
  • Adding in a new data file
  • Quickly adding multiple data files and applying an existing peak profile by manually editing the project (prj) file.
• Quickly adding new multiple data files and applying an existing peak profile by manually editing the project (prj) file. (i.e., add 20 new files to replace 20 old files)
• Project files specify absolute directory paths - and how to get around this.
• Modelling the background:
  • Specifying a more flexible higher order polynomical to fit the background.
  • Using a broadened peak (or several broadened peaks) to model nasty humps or backgrounds - including using the Split Pearson 7 (PVII) to model assymmetric backgrounds.
  • Define the diffraction pattern / spectrum into sub-ranges that can be fitted in a convenient fashion.
• How to toggle on or off the calculated profile of each individual modelled peak.

Worked Examples

• Standard (non-fundamental paramaters) fitting to a single lab powder XRD CuKalpha(1,2) pattern with nice background in one hit (Yttrium Oxide - Y2O3). (Split Pearson on asymmetric peaks and Pseudo Voight on symmetric peaks).
• Standard fitting to a single lab powder XRD CuKalpha(1,2) pattern with nice background in bits (XFIT remembers all!) (Yttrium Oxide - Y2O3).
• Standard fitting to a synchtrotron powder XRD dataset (Silicon metal) - Daresbury beamline 2.3.
• Standard fitting to high-temperature/high pressure angular data digitised from an image plate using the Platypus software (Daresbury beamline XX)
• Using XFIT to calibrate an Energy Dispersive Detector (Daresbury beamline 16.4)
• Using

Real World Examples

• Peak profiling for Indexing and Structure Factor Extraction of a Lithium Titanate Phase

  • Saving a Peak Result file in a Crysfire, Chekcell, etc export happy format
  • Empirical Peak Profiling on lab Powder XRD data for Auto-Indexing and Structure Solution

  • Fundamental Parameters Peak Profiling on lab XRD data for Auto-Indexing and Structure Solution

  • Empirical Peak Profiling on synchrotron data for Auto-Indexing and Structure Solution (Peak Profiling of Cimetidine using XFIT

  • Fitting of Automatic Divergence Slit (ADS) Lab XRD data using Fundamental Parameters Approach - In2O3

Mass Analysis of Data Using XFIT

(The Problem and Solution - the Need for Speed!)

• Using the PRJ Software by Andrew Jupe

  • Basic Demonstration of PRJ in action

• Automating some of the Drudgery out of XFIT - Automation of Repetitive Peak-fitting with XFIT for Win95/NT using a KeyStroke/Macro Recorder-Player for Mass Analysis of Similar Patterns