Aspects of Quantitative Determination by Ion Probe of Fluorine Concentrations in Apatites

Abstract

In studies of F concentrations in apatite crystals by means of secondary ion micro-analysis, it is found that even in a sample with a known and constant F/Ca ratio the recorded ratios of the F and Ca secondary ion currents can vary widely, depending on the experimental conditions of primary bombardment. An attempt has been to explain this behaviour and to devise a way to obtain quantitative atomic F to Ca ratios independent on measuring conditions. Simultaneous recording of the mass peaks of F+, Ca+ and another matrix ion (P+ or C++) appears to offer a solution of the reproducibility problem. This is demonstrated by ion probe measurements under varied conditions in three groups of materials where the F concentrations had previously been determined by macroscopic methods: apatite crystals with about 3% F, whale teeth of about 10-1 % F, and human enamel ob about 10-2 % F.