By far the easiest and reliable way to do a standard XAS experiment at our facility is transmission XAS. There are a few details about the samples that need to be considered.
Quality of the samples: Powder, foil/film, or liquid are all ok.
Amount of sample: Foil or film - preferably one absorption length.
Special requirements for powders: the powder grains should have a smaller thickness than the absorption length.
Standard sample holder: Our standard sample holder is an M8 sized washer (external diameter 16 mm, internal 8.4 mm, thickness 1.6 mm). Label your sample with a permanent fine tip marker on the washer. Attach a piece of a single-sided Scotch tape on one side of the washer, fill in the sample and seal the gasket with another piece of Scotch.
We have an automated sample exchanger system that allows for 15 samples to be loaded in a cartridge for automated sequantial measurements.