QUANTITATIVE ANALYSIS

This page explains the commands for quantitative analysis. It aims at assessing the weights of a number of a number of pure phases in a mixture. The pure phase profiles has to be supplied besides those of the mixtures. It is performed by using the MultiFit or the unfolding approaches. The commands are:

unfold

purephase

rhoin

test

constraint

referw

calib

fitmodel

sam

combine

unfold

Defines the method used for quantitative analysis.

• 0 Multifit approach. It uses the fitting functions of ROOT and the MINUIT library developed at CERN

• 1 Unfolding approach. It uses the unfolding function of the TSpectrum class of Root

• 2 Multifit + Unfolding approaches. Quantitative estimates from the two methods are combined with equal relative weights

purephase

Placed after a file command line, tags the corresponding profile as that of a pure phase. A maximum of 10 pure phases can be managed by the program.

rhoin

Provides the value of the mass absorption coefficient (cm²/g) for each pure phase.

Example:

test

Placed after a file command line, tags the corresponding profile as belonging to the test set for supervised quantitative analysis. The profile should have known weight fraction, set by the command referw.

constraint

Defines a constraint on quantitative assessment of pure phases, as determined by the MultiFit approach.

• 0 independent assessment (default)

• 1 the sum of pure phases weights must be 1

referw

Defines the known weight fraction of the pure phases in the mixture sample. These values are used for comparison with those calculated by RootProf. The command has to be placed after a file command line. It should be followed (on the same line) by a number of values equal to the number of pure phases included in the dataset.

calib

Defines the type of calibration in case of supervised quantitative analysis (whichanalysis 4), to be performed by using profiles with known weight fractions (those tagged by the referw and test commands).

• 0 full calibration. Both pre-processing optimization and rescaling of pure phases is performed automatically (default)

• 1 optimization of the pre-processing method

• 2 rescaling of pure phases

Note: given the long computations, it would be advisable to run RootProf in batch mode by using the linux command

root.exe -l -b -q 'RootProf_v15.C("fileInput")' > outputFile

when using calib 0 or 1. In this case the command savefig 1 or 2 should be added to the command file, to save figures for later inspection.

fitmodel

Defines the type of superposition model for the MultiFit procedure.

• 0  Profiles Y(i) are fitted by the function P0+Sum[PjFj(i)], where P0 and Pj are free parameters of the fitting and Fj are the pure phase spectra. This model is commonly used for phase analysis of X-ray diffraction patterns (default)

• 1 Profiles Y(i) are fitted by the function P0+Sum[PjFj(i+Tj)], where P0, Pj and Tj are free parameters of the fitting and Fj are the pure phase profiles. This model is commonly used to analyze XAS data, where shifts in energy can occur

sam

Command to implement the Standard Addition Method (SAM). It defines the weight fraction of a known compound added to a mixture of unknown phases, which include the known compound. 

Example of application of the SAM: