POSITIVE THERMAL IONIZATION MASS-SPECTROMETRY OF MOLYBDENUM

A technique has been developed to enhance ion yields from molybdenum f or thermal ionization mass spectrometry with a single filament ion sou rce. A molybdenum compound with valency of +6 is reduced to a molybden um (+3) compound by ammonium iodide and ascorbic acid, and is loaded o n the rhenium filament with a mixture of powders of rhenium and platin um. The reduction of the molybdenum (+6) compound depresses its volati lity, and the mixed surface of rhenium and platinum enhances the ioniz ation efficiency. This treatment of filament can be used for other tra nsition elements like hafnium, cerium and thorium.