This project aims to gain a better understanding of laser ablation processes, leading to improved analysis of geological materials, especially sulfide.
In 2015, two new 4 ns pulse-width laser ablation systems (ArF 193 nm and KrF 248 nm excimer lasers) were installed, thus expanding the range of laser microprobes within the CODES Analytical Laboratories. Research was mainly focussed on understanding the impact of laser beam frequency, pulse width, and energy on the ablation of a range of sulfide minerals with small spot sizes. The main outcomes included:
- Improved capabilities for analysis of trace elements in copper-rich sulfide minerals by using the 248 nm 4 ns excimer laser, which reduces signal drop for small spot size analyses (beam size < 25 um). Morphologies of ablation craters in sulfide minerals, produced by different laser microprobes, were compared using a high-resolution FE-SEM at the UTAS Central Science Laboratory, revealing variations in the amount and distribution of melted material.
- Ablation characteristics of pyrite are dependent on the amount and range of trace elements present as micro-inclusions. Pyrites with a large concentration of micro inclusions are characterised by a more regular ablation, leading to a different behaviour of sulfur.
- Demonstration of the ability of the high sensitivity 248 nm LA-ICP-MS system to characterise micron-scale gold rims on pyrite grains by utilising a small beam size (~4 μm).