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Beware! - Cross check with known standards. Source code released under the GNU GPL Software Licence

Diffconv - INEL PSD Spline based Data Calibration software for Windows 95/NT by Stefan Pantos

Generating the Calibration file (using a Silver Behenate and Cubic Y2O3 mixture)

The CCP14 Homepage is at http://www.ccp14.ac.uk

[CCP14 Supported Projects] | [Diffconv Homepage]

The Aim of This

The aim of this is to generate the observed and calculated peak positions for the INEL PSD calibration file which can then be used to convert data files en-masse using Diffconv.

ConTEXT Freeware Text Editor Ultra Edit Shareware/Commercial ASCII text editors can do Column Editing!

ConTEXT Text Editor (toggle Control L for normal and column editing mode) (will also save to UNIX, DOS and Mac ASCII - "Tools, Convert Text to"): http://www.fixedsys.com/context/

The UltraEdit text editor for windows (http://www.ultraedit.com/) can do Column editing/cut/paste and this is the software to install if you wish to save hours cutting and pasting column data into the Diffconv *.pre calibration files.

Obtaining the "Calculated" Peak Positions

Normally the standards you use should have well defined Unit Cells (e.g., Silver Behenate and Cubic Y2O3 mixture) Information on Silver Behenate can be obtained on the Calibration standards for Powder Diffraction Page

Indx for Windows (part of the LMGP Suite) can be used to calculate peak positions to 4 (or more) decimal places if you give the cell constants (when you print the list to Wordpad, Indx prompts for the number of decimal places you wish to calculate to).

There is also a tutorial on Graphical unit cell refinement of the silver behenate C-axis using Celref. Celref can also help you identify HKLs if you get confused with this on your data (especially if you have spurious peaks or poor counting statistics).

Obtaining the "Observed" Peak Positions

NULL Conversion of the Binary INEL data to ASCII

In this case, a Silver Behenate and Cubic Y2O3 mixture is used for calibration

Select the Add Files to add the standard file you wish to convert to ASCII without using any calibration.


Select the list box to bring up the option to open GUFI files.


Now select the now enabled NULL Conversion option.


Select the options and output format and then Convert. You will be asked a few questions depending on the options you selected. Select a step size close to what is expected (0.03 for most INEL systems using GUFI files) and linear interpolation to constant steps has been found to do a decent and fast job.


NULL Converted Silver Behenate and Cubic Y2O3 standard data

The following shows why it can be good to use a Silver Behenate and Cubic Y2O3 mixture. Pretty much the entire range of two theta is covered. The following date is displayed in XFIT for Windows. (In reality, this data has been spliced together from two different samples though the theory is sound!)

Looking at the data in XFIT

Peak Profiling of the Converted Standard Data File

Use your favourite program to profile the obtain accurate "observed" peak positions from the standard data file.

There is also a tutorial on Empirical Peak Profiling of silver behenate using XFIT for Windows.

Editing the *.pre Diffconv Calibration File

Now use a column editor such as the ConTEXT Text Editor to edit a Diffconv *.pre calibration file. You can give this any name you want but it has to have the PRE file extension. (toggle Control L for normal and column editing mode)

The resulting file should look something like the following. You have to correctly tell it the number of data points. Also note that for the present version of the software you have to follow the tab delimited format of the *.pre file or diffconv will crash.

After doing all of this, you can now use the below calibration file to calibrate INEL data en-masse!

K=	7.000000
C=	0.050000

#Observed Channel for the peaks, calculated 2-theta value for peaks
#Calibrasion Data
numOfDataPoints= 67
  1.1961	  1.5136
  2.7202	  3.0275
  4.2508	  4.5419
  5.7651	  6.0571
  7.2737	  7.5733
  8.8470	  9.0909
 10.3675	 10.6101
 11.8702	 12.1311
 13.3801	 13.6543
 14.9761	 15.1800
 16.2769	 16.7083
 20.4154 	 20.4838
 26.1620 	 29.1271
 29.0488 	 31.5191
 33.7135 	 33.7583
 35.8731 	 35.8735
 37.9036 	 37.8858
 39.8594 	 39.8110
 41.7293 	 41.6616
 43.5596 	 43.4473
 46.9894 	 46.8544
 48.6161 	 48.4879
 50.2290 	 50.0811
 51.7295 	 51.6382
 53.3126 	 53.1624
 54.7949 	 54.6568
 56.3011 	 56.1240
 57.7153 	 57.5665
 59.1330 	 58.9862
 60.5518 	 60.3851
 61.9268 	 61.7649
 63.3063 	 63.1270
 64.6448 	 64.4729
 65.9748 	 65.8038
 69.8722 	 69.7185
 71.1569 	 71.0007
 72.4107 	 72.2731
 73.6755 	 73.5365
 74.9316 	 74.7918
 76.1582 	 76.0396
 77.3934 	 77.2807
 78.6216 	 78.5157
 81.0665 	 80.9703
 82.2895 	 82.1911
 83.5126 	 83.4083
 84.7045 	 84.6225
 87.1150 	 87.0443
 89.5118 	 89.4608
 90.7046 	 90.6684
 91.8962	 91.8763
 93.0900	 93.0850
 94.3118	 94.2951
 95.4986	 95.5072
 96.7078	 96.7217
 97.9057	 97.9392
 99.1135	 99.1604
101.5443	101.6160
102.7680	102.8517
103.9932	104.0935
105.2398	105.3421
106.4736	106.5981
108.9636	109.1359
110.2357	110.4192
112.8205	113.0192
114.1205	114.3378
115.4452	115.6703
116.7714	117.0179

[CCP14 Supported Projects] | [Diffconv Homepage]

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