Vapor detection using adsorptive solids probed by X-rays

Activated carbon is used widely as a filter medium for trapping gases and vapors from the air. It is effective because of its large capacity even at low concentration levels. X-ray absorption measurements recently have been conducted on activated carbons before and after they have adsorbed certain organic gases. The measurements have shown that the X-ray absorption technique, when applied to porous adsorbing solids, is very sensitive for detecting low levels (less than 1 ppm) of many gases and vapors. The method is especially good for detecting compounds containing atoms having atomic numbers greater than 14. This is due to the increasing interaction of X-rays with matter as atomic number increases.