ION MICROPROBE DETERMINATION OF WATER IN SILICATE-GLASSES - METHODS AND APPLICATIONS

Ion probe measurements offer the advantage of in situ determination of water content with a few micrometres spatial resolution. After a brie f review of ion microprobe procedures used for the determination of wa ter concentration in silicates, we examine three important effects on analytical precision: (1) the effect of energy filtering an the backgr ound; (2) the variation of the H/Si ratio with time; and (3) the depen dence of the H/S1 ratio on the composition of the matrix, which requir es the use of standards close in chemical composition to the unknowns. , Finally, applications of this method to the determination of water i n glasses quenched from water-saturated melts, to experimental product s consisting of a mixture of glass and crystals, and to natural melt i nclusions illustrate the advantages and the limitations of the ion mic roprobe.