A STUDY OF TECHNEGAS EMPLOYING X-RAY PHOTOELECTRON-SPECTROSCOPY, SCANNING-TRANSMISSION ELECTRON-MICROSCOPY AND WET-CHEMICAL METHODS

Scanning transmission electron microscopy (STEM), coupled with energy dispersive X-ray analysis (EDS), X-ray photoelectron spectroscopy (XPS ) or radionuclear chemical methods, indicates that the active agent in Technegas is either polymeric TcO2 [i.e. (TcO2)(n)] or (TcO2)(n) boun d to a carbon nanoparticle. The particle size observed using STEM is i n good agreement with other published results. XPS has also been used to investigate technetium residues remaining on spent crucibles. The c hemical form of technetium in this residue is quite different to the f orm detected in the aerosol particles. We conclude that the small frac tion that migrates into the crucible framework upon resistive heating is reduced to either metallic technetium or carbidic forms, with the r emaining nuclide evaporating as (TcO2)(n) with or without carbon befor e complete reduction can occur.