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Simple untreated wire emitters can be used for field desorption of electrolytic solutions, e.g. acids or substances containing alkali salts. The ionization is achieved by the attachment of protons or alkali ions to molecules in the condensed phase which are subsequently desolvated by the action of high electric fields. This field desorption mode is demonstrated and discussed for a few characteristic examples. It is shown that the addition of substances of high viscosity and low vapour pressure in the liquid state favours the field desorption behaviour of many compounds. In general the mass spectra of untreated wires are less complicated than those of activated emitters since field ionization processes occurring at the tip of the field-enhancing microneedles are avoided.

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Positive and negative ion mass spectra of organic polymers were recorded using the Laser Microprobe Mass Analysis (LAMMA) technique. The mass spectra are characteristic of both the hydrocarbon backbone of simple straight-chain polymers [polyethylene, poly(viny1 chloride), and poly(tetrafluoroethy1ene)l and of slight changes in side chain functionality [poly (phenyl methacrylate) and poly (benzyl methacrylate)]. The spectra show 34 7