On Friday 27 August 2004 09:04 am, Mauricio wrote:
I'm in troubles when trying to work with my L3-Pb absorption data with Athena. I'm a beginner with the Ifeffit stuffs... Also, sorry if this report is not correctly posted, but I will try to give you the maximum information I can...
Let's go. The data were taken at the Brazilian syncrotron laboratory, and the "important" data are in columns 3 (energy), 4 (Io) and 6 (It). The file is of the following form:
Hi Mauricio, It seems that the problem is with the first two columns, which contain date and time information. Athena relies upon Ifeffit's notion of what is and is not a line of data in a file. For Ifeffit, a line of data is a line which contains only strings which are recognizable as floating point numbers. Strings such as "04/02/04" and "12:32:51", though obvious to the human reader, are not interpretable as numbers by Ifeffit. So Ifeffit reports that it could not find *any* lines containing data in your file. Athena should have complained about that without issuing an error message, but apparently there remains a problem. The immediate solution is to edit the data file and remove the first two columns of data. I suspect that Ifeffit and Athena will then be happy with your data files. There are two more permanent solutions. 1. Convince the person who maintains the data acquisition software at your beamline to use a file format that Ifeffit can read. Alternately, disable the recording of date and time with every data point. Frankly, it seems silly to record the date at every point. EXAFS scans are typically on the order of minutes. It should be sufficient to record the data once at the top of the file. The same is probably true of the time, although I can imagine situations where the time is useful information. In that case, recording the start time at the top of the file and recording a column of elapsed seconds serves the same purpose and would not confuse a program expecting floating point numbers in the data columns. 2. It may be impossible for some reason to have the data file format changed, but there are people doing exafs and wanting to use Athena. That was the case with beamline X10C at NSLS. There is special code in Athena to recognize a data file from X10C and rewrite it in a way that Ifeffit will handle. I am willing to do the same for other beamlines, but I would need several examples of data to work with. B P.S. That was a dandy problem report. You gave me sufficient information to understand the problem, which is all I ever ask for. Thanks! -- Bruce Ravel ----------------------------------- ravel@phys.washington.edu Code 6134, Building 3, Room 405 Naval Research Laboratory phone: (1) 202 767 2268 Washington DC 20375, USA fax: (1) 202 767 4642 NRL Synchrotron Radiation Consortium (NRL-SRC) Beamlines X11a, X11b, X23b National Synchrotron Light Source Brookhaven National Laboratory, Upton, NY 11973 My homepage: http://feff.phys.washington.edu/~ravel EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/