## 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.

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).