DESORPTION IONIZATION OF INORGANIC-COMPOUNDS IN FOURIER-TRANSFORM LASER MICROPROBE MASS-SPECTROMETRY WITH EXTERNAL ION-SOURCE/

Application of FT LMMS to inorganic compounds offers the advantage of direct speciation. This means that signals which refer to intact analy te molecules are detected. Current concepts of desorption and ionizati on in LMMS are mainly based on time-of-flight data and hence on ions f ormed during the laser pulse. This paper focuses on indications about the desorption and ionization mechanisms for inorganic compounds that can be deduced from the mass spectra in our FT LMMS database. Specific ally, the occurrence of continuing ion formation during several hundre ds of microseconds is demonstrated. These data are relevant to the pos sible role of selvedge ionization versus direct ion emission from the solid state.