Introduction

PyXMRTool is a flexibel Python3 package for the analysis of Resonant X-ray Reflectivity measurements built on the package Pythonreflectivity. More specifically it allows to fit a model of a heterostructure to the reflectivity data.

The package has a strict object oriented design. It should enable the user to add together the building blocks in a script. The package has a modular structure to account for different topics.

The module SampleRepresentation contains everything needed to build the model of the sample. In the end, an object of the class SampleRepresentation.Heterostructure contains all the necessary information and serves as model representation.

The above mentioned module or its classes resp. use parameters which should be fitted to the data. To allow for a centralized handling of parameters instances of Parameters.Fitparameters are organized within a parameter pool. Like this every parameter “knows” how to get its value from an parameter array. All this and some more can be found in the module Parameters.

The module Experiment deals with the experimental setup, which polarizations are measured, parametrized background etc and it deals with the measured data. All this is represented by an instance of the class Experiment.ReflDataSimulator. It also delivers the sum of squared residuals (SSR) or the residuals themself in dependence of a parameter array.

Fitting is then the procedure of minimizing this SSR by varying the parameter array. Self-written fitting routines can be found in the module Fitters, but it is better to use professional ones (see Fitting). But the module Fitters contains also a tool to scan for different fixpoints in the parameter range, to explore it using scipy.optimize.least_squares. See Fitters.Explore().