Optimisation of laser wavelength in the ablation sampling of glass materials

Glass is an excellent matrix for use in the immobilisation of waste materials. In order to more thoroughly understand how this material behaves over long periods of time it is important to be able to carry out spatially resolved chemical analysis of the material. One technique which offers spatially resolved chemical and isotopic analysis is laser microprobe inductively coupled plasma mass spectrometry. The laser is employed as a high resolution sampling probe and the inductively coupled plasma mass spectrometer provides the analysis. For the sampling technique to be valid it is imperative that the material ablated is representative of the original matrix. Unfortunately glass can be a difficult material to ablate at certain wavelengths due to its transparency and ability to reflect the radiation. This can result in ablation of material which is not representative of the matrix. This paper will examine the effect of laser wavelength on the ablation process. Chemical analysis by inductively coupled plasma mass spectrometry will be used to examine the composition of the ablate.