Radio frequency glow discharge mass spectrometry for the characterization of bulk polymers

A radio frequency (rf)-powered glow discharge (GD) atomization/ionization source is utilized to determine the applicability of the technique for direct polymer analysis. A series of PTFE-based polymers are studied to assess their fingerprint mass spectra and to distinguish each sample by its differing base peaks and relative peak intensities. A parametric study with respect to discharge gas pressure and rf power is conducted to evaluate their respective roles in the sputtering process as well as possible ionization mechanisms. The results of the GD sputtering processes are examined by scanning electron micrographs of a sputtered PTFE surface. Excellent discharge stabilization characteristics ( < 3 min) were observed in temporal response curves. Internal stability with respect to signal intensity is observed to be < 5% RSD for samples of different thicknesses. Finally, the ability to obtain depth profiles of layered samples was demonstrated for the case of a Cu layer deposited on a PTFE substrate.