Program DIFPATAN has been written for the evaluation of XRDP profile parameters either by direct analysis or by profile fitting.

Direct profile analysis consists in direct determination of profile parameters usually after the subtraction of background and K_a2 elimination. The profile fitting approximates diffraction peaks by analytical functions:

• Pearson VII function (with Gauss-like and Cauchy functions as special cases)
• split-Pearson function
• asymmetric Pearson function
• pseudo-Voigt function
• rational function

The program includes intensity corrections for different geometries :

• conventional Bragg-Brentano in symmetrical theta-2theta geometry
• asymmetrical geometry used for stress measurement (the so-called W- goniometer )
• asymmetrical geometry used for stress and texture measurement (the so-called y- goniometer or side inclination method)
• thin film Seemann-Bohlin geometry with the constant angle of incidence
• transmission Seemann-Bohlin geometry

The program also includes the correction for the polarization of synchrotron radiation. The corrections can be performed either before or after the fitting.

Input

Data files can be of different ASCII format (this can be specified in Configuration file).

Output

Diffraction patterns (including those modified by the program) can be stored in a two or three column format suitable for many spreadsheet and graphic programs. Current graphic window can be saved in HPGL format suitable for plotters and most of laser printers.

Profile parameters found by the program are saved in a tabular ASCII format.

The program runs in text and graphic modes.

Main menu (in text mode) consists of the following parts :

Files
Graphics
Environment
Output
Fitting
and Quit.

How to control the program.

Select items by <Enter>. Go back to the top submenu by <Esc>.

Mouse control is not supported. Menu items can be selected by arrow keys or by highlighted letters (in text mode) or first letters (graphic mode). The latter way is faster.

The program offers different possibilities (fitting, comparison and combination of files, comparison with known peak positions etc). However, the main application may be the fast profile fitting of segments of powder diffraction pattern. The program is not suitable for completely unexperienced people but it was writtenas a handy tool for X-ray diffractionists. It can be run also on very slow computers.

Quick start

The program has been written in Turbo Pascal using some special routines for menus and Input/Output operations. Larger modification of the program is not easy.

Mouse control and overcome of 640 kB memory limit cannot be expected in near future