Positive and negative ion ejection in the mass range below 200 Dalton is observed for perfluorinated poly-ether surfaces subjected to electron- and ion-beam irradiation. The exciting projectiles are Ar+ ions of 300 and 4000 eV and electrons of 3000 eV. The main positive ions found are fragments of CF3 + ions. Larger ions are found with lower probability. The main negative ion observed is F. The results show that the liquid-vacuum interface is formed by CF3 groups from the polymer.