Selective resonance enhanced multiphoton ionization of aromatic polymers in supersonic beam mass spectrometry

Abstract

Various polymers have been studied using a pulsed laser evaporation method for volatilizing these species and entraining them into a supersonic jet expansion followed by resonance enhanced multiphoton ionization (REMPI) detection in a reflection time-of-flight mass spectrometer. In most cases the monomer is detected as the dominant ion, although sometimes smaller characteristic fragments are observed instead. Fragmentation of the monomer can also be produced for structural analysis. However, larger oligomers are rarely observed with any intensity unless the average molecular weight distribution is less than 1000. In addition, REMPI at 266 nm is shown to be a means of selectivity detecting absorbing aromatic polymers in polymer blends without interference from aliphatic or non-aromatic polymers. Among the polymers studied are polystyrene, EPON epoxy resins and various polyamides.