Beamline scientist does energy calibration of the germanium solid state detector
by using Fluorescence lines of silver at 22.104 keV (K\({\alpha}\)) and
24.942 keV (K\({\alpha}\)1), and gammas from 109Cd (88.04 keV) and 57Co (122.10 keV)
at the beginning of each beamtime cycle. Parameters of energy calibration (\(Energy = CAL\_OFFSET + CAL\_SLOPE \cdot Channel\)) can
be found in the header of the EDXD data file.
In some cases the energy calibration has to be done from different radio-nuclei sources and the spectra recorded in separate acquisitions. In this case, define the appropriate fluerescence lines ROI’s and save a separate data file for each acquisition. With the Energy calibration window open for one of the spectra, fluerescence ROI’s from additional files can be loaded (by clicking Load more regions…) and used togeth to compute the calibration coefficients.
Beamline scientist does 2\({\theta}\) angle calibration at 7°, 15°, 23°, and 31°
using unit-cell volume of Au, and make linear equation to calculate 2\({\theta}\) angle.
The following is the procedure for 2\({\theta}\) angle calibration:
Collect Au EDXD pattern.
Make ROIs for all Au peaks using JCPDS data at 0 GPa.
Select Control ‣ Calibrate 2theta… on Menu bar.
Please remove weak or overlapping peaks by unchecking them in the column ‘Use?’.
Note
Because the MCA does not have background subtraction feature, background slope at low energy (<~25 keV) probably due to absorption influences on determining peak position. It is better not to use low energy data for 2\({\theta}\) angle calibration. Typically, at 2\({\theta}\) of ~15 °, the first and second peaks show marked deviation from other peaks.
Click Compute 2-theta.
2\({\theta}\) value appears in the ‘2\({\theta}\)’ box.
Then, please click OK to apply the 2\({\theta}\) calibration.
Note
The 2\({\theta}\) calibration result is also saved in the header of the data file.
