International Union of Crystallography

Defining X-ray absorption techniques

[Isabella Ascone]The Online Dictionary of Crystallography, established by André Authier for the International Union of Crystallography in 2006, is an important and valuable guide to terminology in crystallography and its closely related disciplines. In an effort to consolidate its status as an authoritative reference, IUCr Commissions are encouraged to work on definitions that fall within their specific area of interest.

In the increasingly active field of X-ray absorption techniques, over 12 000 papers have been published in the last five years, and the Commission on XAFS has made it a priority to draw up a set of definitions contributing to the Online Dictionary. An important objective of this endeavour was to identify ambiguous or incorrect usage of XAFS expressions in the scientific language. Rather than attempt to formulate "perfect" definitions, we set out to propose currently used definitions and to allow the possibility of the community's improving them through open debate.

The first document produced by a Working Group and Advisory Committee on XAFS Nomenclature is now available from the Commission website. Specific comments from individual members of the Working Group and Advisory Committee, and from other experts, will be posted separately. I welcome considered comment on these proposals from any member of the community; please direct comments to the Commission Chair who will involve the Working Group or Advisory Committee as required.

Isabella Ascone (
Chair, Commission on XAFS