Analyzing hydrogen (H₂O) in silicate glass by secondary ion mass spectrometry and reflectance Fourier transform infrared spectroscopy

The water contents of silicate glasses can be measured by secondary ion mass spectrometry (SIMS) and Fourier transform infrared (FTIR) spectroscopy. For SIMS, one of the impediments to quantitative analysis is uncertainty in the effect of sample chemistry on calibration, while for FTIR, sample preparation is often the most difficult step. A wide range of hydrogen-implanted silicate glasses was tested to see if a general relation between sample chemistry and calibration factors for SIMS could be formulated. The results show that while some compositions are suitable for H implantation (matching earlier calibrations based on experimentally hydrated samples), other H-implanted compositions show very low H signals. We suggest that the difference in atomic environment between implanted H vs. dissolved H may cause low count rates. Using the reflected IR spectrum simplifies sample preparation. Reflection IR measurements of experimentally hydrated glasses show that the H₂O content of basaltic, andesitic, and rhyolitic glasses can be quantified down to ≈0.5 wt.%. Lateral resolution is limited by intensities of current IR sources to ≈100μm.