Field extraction of ions from liquid solutions with the use of polymer track membranes

The general principles of the electric field assisted ion evaporation in the membrane ion source are considered. In the ion source, the liquid sample under investigation is placed in narrow channels of a polymer track membrane, which separates the liquid sample at atmospheric pressure from the vacuum chamber. Stability of the liquid at strong electric fields is provided by a choice of the diameters of channels and the liquid-polymer contact angle. The electric charge on the vacuum-polymer interface is of great importance for creation of the strong electric field near the liquid-vacuum interface. Such a conclusion is made from the computations of the electric field in the framework of the model developed. The mechanism of the electric field assisted evaporation of ions is discussed to explain the observed mass spectra for the ions extracted from liquid. (c) 2005 Elsevier B.V. All rights reserved.