X-ray Methods Subcommittee Agenda and Minutes

X-ray Diffraction Methods Subcommittee
16 March 2005
ICDD Headquarters 
Chairman - D. Balzar

1. The minutes from the March 2004 Meeting were approved.

2. Board of Directors’ Liaison Report – There were no previous motions to be reported on.

3. Report on the activities of the committee in the previous period - Scott Misture

a. X-ray Optics: S. Misture reported on the activities of the Optics Task Group. He has collected a significant amount of data that includes a range of optics and users. The question now is how to put everything together in a publishable form. He will distribute a draft set of data to the members of this subcommittee in graphical form.

b. Temperature Standards for Non-ambient Condition Experiments: This is a focus topic of the upcoming BCA meeting and may give us ideas such as which standards should be used. S. Misture compiled a list of standards that have not yet been tried. Scott and his postdoc are in the process of writing a paper to be submitted to Powder Diffraction and have offered co-authorship to anyone who would like to contribute.

4. Report on the newly formed Task Group on 2-D detectors - Bob He
The Task Group met on Monday, March 14, 2005, and considered several issues. Bob He gave a presentation on Linear and Area Detectors. He emphasized corrections that have to be applied when collapsing 2-D data into a 1-D intensity-diffraction angle trace for phase ID. This should be of interest to ICDD because it involves PDF use. Bob stated that he already published a paper on the subject of texture corrections (A simplified procedure for obtaining relative x-ray intensities when a texture and atomic displacements are present, Baoping He, Satish Rao, and C.R. Houska, J. Appl. Phys., 75(9) 4456-4464 May 1994).

5. Other topics of interest in the next period - Davor Balzar
D. Balzar summarized responses and suggestions obtained from the subcommittee members based on his e-mail inquiry sent out to members in December 2004. There was very positive feedback on the Bob He's initiative to study issues regarding 2-D detectors. Second, a suggestion was made that ICDD should propose to the manufacturers of diffraction equipment a unique raw-data file format. A discussion that followed indicated that perhaps manufacturers would be ready at this time to seriously consider such an initiative. Davor proposed the formation of another Task Group to consider this problem.
Davor also informed the subcommittee about other suggestions by the membership (notably, a study of relative intensities obtained by Co radiation, considering the PDF-4/Organics file and the Linus Pauling File in relation to this subcommittee's role, and others).

The following motions evolved from this meeting:

Motion 1:
2-D Detectors Task Group (led Bob He and Kris Kozaczek) is appointed and charged with assessing how much are collapsed diffraction patterns affected by corrections during a conversion from 2-dimensional to 1-dimensional data set.

Motion 2:
2-D Detectors Task Group is charged with studying the effects of defocusing on 2-dimensional diffraction patterns.

Motion 3:
A Raw Data File Format Task Group was formed (led by Peter Zavalij) and charged with proposing a universal raw data file format to manufacturers of diffraction equipment. The Task Group will first consider whether the CIF format, proposed by IUCr, can be utilized for this purpose.