Fragmentation under electron impact and vapour composition of tungsten, niobium and tantalum pentafluorides

A summary is presented of the mass spectrometric investigation of fragmentation patterns and vapour compositions of WF5, NbF5 and TaF5. A brief description is given of the mass spectrometer - Knudsen cell system and its use in the experiment. Mass spectra of saturated vapours and appearance potentials of ions are given. The following information is also given: metastable ion transitions, ratios of ion intensities in mass spectra, and vapour compositions of the pentafluorides. From the temperature dependence of ion intensities combined with effusion rate measurements, thermodynamic values for the predominant vaporization processes are derived. (U.K.)