Application of atomic and molecular primary ions for TOF-SIMS analysis of additive containing polymer surfaces

The influence of primary ion mass and composition on secondary ion emission of the additive Irganox 1010 (m = 1176 u) in polyethylene was investigated . O+, Ar+, Xe+, O-2(+), CO2+, SF5+, C7H7+, C10H8+, C6F6+, and C10F8+ with a total energy of 11 keV were used as primary ions under static secondary io n mass spectrometry (SIMS) conditions. Positive and negative molecular seco ndary ions characterizing the additive were determined and their yields wer e evaluated. For all characteristic secondary ions we found a strong yield enhancement w ith increasing mass for atomic primary ions and increasing number of consti tuents for molecular primary ions. This yield enhancement is saturated once the molecular primary ion is made of more than six heavy atoms. In additio n this yield increase depends on the mass and structure of the considered s econdary ion. We did not find any evidence for an influence of the chemical composition of the applied molecular primary ions on the secondary ion emi ssion when static SIMS conditions were met. The improved imaging capabiliti es of molecular primary ions was demonstrated by comparing focused Ar+ and SF5+ primary ion beams when mapping characteristic secondary ion emission f rom a structured additive containing polypropylene surface. (C) 2001 Publis hed by Elsevier Science B.V.