Abstract: A focused ion beam is directed toward a sample to be analyzed while iodine vapor is directed toward the sample. The iodine vapor, which is formed by heating solid iodine to a temperature of 30.degree. C. to 50.degree. C., aids in sputtering of material impinged by the ion beam and in enhancing the conversion of neutral to ionic sputtered species. A quadrupole mass analyzer is positioned for receiving secondary ions sputtered from the sample whereby chemical analysis is accomplished. The iodine may be initially handled in a solid state, exhibiting a low vapor pressure, and is then heated to moderate temperatures inside a focused ion beam system without presenting a toxic hazard or requiring external plumbing.