Poly(ethylene terephthalate) track membranes (TM) were recently suggested for electrostatic injection of charged species into time-of-flight mass spectrometers (TOF-MS). A Schottky-type barrier reduction was investigated using a thermally activated extraction regime. A brief description of the physical processes involved is given. A wide range of the externally applied electrical potential, Φ, was covered. Collector currents were found to exhibit an activation-like behavior, ~exp(-ΔF/k(B)T), whereas the free energy difference, ΔF, across the liquid-to-vacuum boundary is such that ΔF = ΔF0 - ΔFΦ. An externally controlled term, ΔFΦ, was also sensitive to the salt concentration for the KCl/glycerol solutions used. A dramatic decrease of ΔF(ΔΦ → 0) was found for an increasing charge cartier concentration. In accordance with the thermionic emission mechanism of ion extraction, the Schottky effect has manifested itself in ΔFΦ ~ Φ 1(/)2. (C) 2000 Elsevier Science B.V.