TUBE ION-SOURCE FOR THE STUDY OF CHEMICAL EFFECTS IN SURFACE-IONIZATION

An ion source has been developed in which gas phase ions are sublimed from bulk powders contained in a refractory metal tube. The outside of the tube is heated by electron impact, and the ions are emitted from an opening in the end of the tube. Regulation of the electron emission current makes it possible to maintain a constant source temperature from 700 to 2200 K. The design easily accommodates a wide range of powders/blends making it possible to study bulk chemistry effects on the formation of atomic and molecular ions and easily survey a wide range of materials under well controlled temperature conditions. Examples are given of gas phase perrhenate anion production which show that ion production from these bulk powders is controlled by the same chemical and physical mechanisms as thin-layer systems on heated filaments.