We want to read a diffractogram into Frida-1 so that we can apply an absorption correction. The data are given in a file containing:
2θ value normalized number of counts error of the norm. number of counts
Start Frida in the directory you have the data in. (You don't really have to but it spares you indicating the whole path to the files)
IDA () fm make your own IED file : File name ? some_name (not the file name of the data but the name Frida will give to this file in its memory) and Title ? some_title (also for Frida to use later on) x Coordinate name ? 2th Unit ? y Coordinate name ? S(2th,w) Unit ? meV-1 z Coordinate name ? w Unit ? meV Input mode : (1) enter x coordinates first (2) set x on equidistant grid (3) enter x-y pairs (4) enter x-y-d triples (5) select from multicolumn input (6) dito, including z Option  ? 4 Input mode for z : (1) for each spectrum, just enter z (2) take z from a header block Option  ? now everything is ready for reading the data; for reading from a file, use "\i <file-name>". make spectrum no. 1 Enter header line containing z (or " " to stop) 0 and now the data themselves : Enter data lines; enter " " to stop: > \i name_of_your_file (if it is not in the folder you started Frida from, indicate the path, too)
Note that we specified the energy transfer as z-value and set it to zero.
When Frida asks for the last value, hit return. The second z-value will be queried, hit return again. This will finish the data set. A file containing one spectrum ( = energy), S(2θ,ω=0) vs 2θ, is created. Now, we have to denote the incident Energy of the neutrons with:
IDA (1) er Modify parameters (<list>,a,-) [-] ? a Add parameter: Coordinate E0 And its unit meV parameter: E0 present value for file 1: 0.00000000 meV Modification (val,f,n,u,z,d) [none] 4.3623 (corresponding to 81.81/λ<sup>2</sup>) 1 E0 meV 4.3623000 Modify parameters (<list>,a,-) [-] ?
As the absorption correction expects the x-axis to be ω and z to be 2θ, we exchange x and z with
generating many spectra, each containing only one point.
After applying the absorption correction, one can change back to one spectrum using