Software: SmartLab Studio II

SmartLab Studio II (SLSII) is an integrated software package for X-ray analysis from measurement to analysis.
In this section, we will introduce the Measurement plug-in for measurement and the PDF plug-in for analysis.

Measurement plug-in

 For a total scattering measurement, mirror adjustment, optical system adjustment, capillary center position adjustment, and profile measurement with dedicated detector energy mode are realized, and anyone can easily execute from adjustment to measurement.

Figure 12. Description of element replacement at the time of optical system adjustment

PDF plugin

 The complex PDF analysis procedure can be represented as a flow diagram and analyzed step by step.
In this section, we will introduce the S(Q) calculation, PDF calculation, and RMC modeling.

S(Q) calculation

 When calculating S(Q), the sum of the Compton scattering and atomic scattering components is displayed to confirm that the interferential scattering intensity from the sample has been correctly extracted.

Figure 13. The S(Q) tab on PDF plug-in.

 Figure 14 shows an example of how the intensity-corrected profile (red) matches the atomic scattering factor (black). If they match, the curve of the atomic scattering factor runs through the center of the intensity-corrected profile, and the calculated S(Q) profile (green) oscillates periodically around 1 on the second vertical axis (Figure 14 left). However, if they do not match, the S(Q) profiles are rightward sloping, which implies that the atomic number ratios and absorption calculations for the sample are incorrect (Figure 14 right).
 The PDF plug-in also makes it easy to determine if the analysis is good or bad in this way. By the way, baseline correction of S(Q) distortion by polynomial approximation has also been reported, but it should be noted that it may cause loss of true information on the short side.

Figure 14. S(Q) Good or bad calculation Left: Good analysis example; Right: Bad analysis example

PDF calculation

 The PDF calculation screen is shown below. If there is crystal structure information, etc., the bond distance is automatically calculated and overlaid on the profile with a blue line. Peak positions are also searched, making it easy to obtain peak position information. Of course, $g(r)$, $G(r)$, $R(r)$ and $T(r)$ are all supported and can be converted to each other with a single click.

Figure 15. $G(r)$ Calculation screen

 Unlike the S(Q) correction by polynomial approximation, SLS$\mathrm{I\hspace{-.01em}I}$ has a ripple rejection function. The figure shows their effects in G(r). The window function has the effect of suppressing oscillations due to Fourier transform truncation errors. The ripple rejection correction removes non-physical vibration components below the coupling distance set by the PDF plug-in's feature correction from S(Q) and, thus, extra vibration can be calculated without including the extra vibration in $G(r)$. This allows the fitting accuracy of the structure estimation by $G(r)$ to be improved.

Figure 16. $G(r)$ with window function and ripple correction applied

RMC calculation

 Although RMCProfile is a well-known program for the RMC method, we have also implemented RMC functionality in the PDF plug-in. Currently, the RMC implemented in the PDF plug-in supports the estimation of local structures in crystal structures. With conventional RMC, it is difficult to set parameters, and it takes a lot of time to learn how to use RMC. However, RMC implemented in the PDF plug-in automatically sets parameters, so RMC can be run with only the minimum necessary parameters.

Figure 17. RMC calculation