Reading $I_{0}$ files

One way to get an $I_{0}$ spectrum is to use a hole in the specimen to measure the incident flux in each image. Sometimes this is not possible or desirable; in this case, one may wish to use an incident flux spectrum that was measured in some other way. The spectrum should be saved in a simple ASCII format of (eV,flux in kHz) stored line-by-line, such as an Excel comma space value .csv file, or a .xas file (comment lines that start with text or things like ``!'', ``#'', etc. will be ignored). You should make sure that this file was recorded under similar conditions, like the same slit settings, ring current, and so on. You can of course adjust for this when you create the $I_{0}$ file. You can manipulate these comma, space, value .csv files with Excel, or the read_csv.pro and write_csv.pro routines in the X1 IDL library located here.