Reference Intensity Ratio (RIR) method for quantitative analysis

The so-called "Reference Intensity Ratio method" (RIR-method) presented by de Wolff and Visser [1] is used automatically for (semi-) quantitative analysis if at least two entries have been selected as matching. The quantity (weight %) of each selected phase/entry is displayed in the "Quant.(%)" column of the match list and of course also in the report.

The RIR analysis is based on intensity scale factors that are calculated automatically for all entries/phases in the match list. For this, the intensity differences between reference entry peaks as well as their correlated experimental counterparts are minimized using a least-squares refinement. In addition, the difference between the profile calculated from the match list entry peaks and the experimental profile is also minimized by least-squares refinement.

Note that the RIR analysis can only be carried out if all matching entries contain I/I_c factors. If only one of the selected entries does not contain an I/I_c factor, the values for the remaining selected entries will not be displayed as well ("n.a." is given in the "Quant.(%)" column of the match list). As an exception, you can activate an option to let Match! use a standard I/I_c factor of 1.0 which might be helpful in some situations.

You should check if an entry contains an I/I_c factor before selecting it, by taking a look at the column "I/Ic" in the candidate list in which a corresponding value must be given.

Note:

All entries in the free-of-charge COD reference database provided by Crystal Impact contain calculated I/I_c values.
You can also perform the RIR quantitative analysis explicitly, by running the "Reference intensity ratio (RIR)" command at the top of the "Quantify" menu.
As an alternative to the RIR-method, you can also use the Direct Derivative (DD) method proposed by H. Toraya [2]. This more recent approach does not depend on I/I_c values and is also more accurate in most circumstances.

Reference:

[1] P.M. de Wolff, J.W. Visser, “Absolute intensities”, Rep. 641.109 Technische Physische Dienst, Delft 1964.
[2] Hideo Toraya, "A new method for quantitative phase analysis: Direct derivation of weight fractions from observed intensities and chemical composition data of individual crystalline phases", Rigaku Journal 34(1), 3-8 (2018).