Poly(aryl-ether-ether ketone) (PEEK) films irradiated with 1-MeV and 2-MeV ${\mathrm{O}}^{+}$ ions were exposed to positron beams to measure the positron annihilation Doppler broadening as a function of the positron energy. The annihilation lines recorded at relatively low positron energies were found to become broader with increasing irradiation dose, suggesting that positronium (Ps) formation is inhibited in the damaged regions. The positron data were compared with the results of dynamic hardness and electron-spin-resonance measurements. The slow-positron Doppler broadening technique is found to be a useful means for damage-depth profiling of Ps-forming polymers.

• Received 24 February 1995

DOI:https://doi.org/10.1103/PhysRevB.52.823