Laser Ablation Laboratory

The YAG laser is operated at 35 A at a vacuum of circa 10^-7 Torr at a wavelength of 1064 nm. The diameter of the focused beam is about 10µm. The CO₂ gas (from carbonates) released from the sample is, after purifi cation, transferred to a Finnigan MAT 251 mass spectrometer equipped with a microinlet.

General Applications

• laser micro sampling is an efficient way of producing CO₂ from very small samples with high spatial resolution for Carbon and Oxygen isotopic analyses
• good visual control on a microscopic scale reduces the risk of misinterpretation which often could be the case with bulk analyses
• spot ablation sampling as well as stripe ablation makes it possible to perform a continuous monitoring of gradients without losing material due to cutting

Cultural applications

• the laser ablation technique provides an effective measure of weathering effects on carbonaceous stone material
• the penetration of a conservation agent can be followed inside the stone and the result be compared with untreated samples
• after this quality test a regular monitoring can be done by laser ablation of the effect of the conservation treatment for further maintenance
• it is possible from the C and O isotope ratios to trace a building stone back to its quarry, which is essential for future restoration work

Geological Applications

• to elucidate the relative timing of various episodes of carbonate mineral precipitation in reservoir sandstones based on their petrography and isotope signature distributions. This information is used as important input to reservoir modelling
• to map fluctuations in cave ground water origins from the last ice age up to today by micro laser ablation on sliced wafers of stalagmites (Calcium Carbonate)