Comparison of single pulse, multiple dosage, and 2D oversampling / deconvolution LA-ICPMS strategies for mapping of (ultra)low-concentration samples

Exploring the Benefits of Ablation Grid Adaptation in 2D/3D Laser Ablation Inductively Coupled Plasma Mass Spectrometry Mapping through Geometrical Modeling

“…Both the orthogonal and hexagonal grids can be contracted to yield a smooth post-ablation surface for all crater profiles ( n (□) and n (○) in the range 2–20) with a normalized average depth of one, although more contraction is necessary for lower super-Gaussian orders. Smooth, deeper ablation layers are associated with overlapping craters and may be responsible for blurring in LA–ICP–MS image maps . Nevertheless, for the orthogonal grid (Figure A), 2D overlapping of square spots still yields smooth depth layers at a normalized depth of approximately four for all crater profiles n (□), whereas deeper, smooth layers can only be generated at extreme overlapping of ablation craters with super-Gaussian orders less than 10.…”

“…Smooth, deeper ablation layers are associated with overlapping craters and may be responsible for blurring in LA−ICP−MS image maps. 8 Nevertheless, for the orthogonal grid (Figure 4A), 2D overlapping of square spots still yields smooth depth layers at a normalized depth of approximately four for all crater profiles n(□), whereas deeper, smooth layers can only be generated at extreme overlapping of ablation craters with super-Gaussian orders less than 10. For the hexagonal grid (Figure 4B), the overall post-ablation surface smoothness seems less affected by pinpoint accuracy in the selection of the contraction parameters, as can be seen from the much broader purple regions compared to the orthogonal grid, and the fact that the overall depth range is narrower, as visible from the limited color range.…”

“…This geometrical modeling process can be performed by contracting the grids, either by equal reduction of the spot distance in both the x - and y -directions or through asymmetrical contraction. Additionally, we simulated how contraction of the grids can influence the image quality based on earlier developed computational protocols. ,, …”

“…Additionally, we simulated how contraction of the grids can influence the image quality based on earlier developed computational protocols. 8,19,20 Geometrical Modeling Concept. Conventional single pulse LA−ICP−MS mapping typically employs an orthogonal ablation grid based on the instrumental beam size, implying that round and square beam profiles with the same beam size have the same ablation grid and produce the same pixel size (Figure 1A).…”

“…When the ablation grid is contracted, the overlapping of ablation spots increases the laser spot density and results in more pixels being mapped in the same area when using single pulse LA–ICP–MS. This can lead to improved image quality, but if overlapping becomes excessive, it may cause blur . One of the potential benefits of hexagonal mapping is the fact that hexagonal pixels mimic the human visual system through hexagonal arrangement of sensory cells in the retina, fewer contour artifacts, better edge definition, higher pixel density, higher symmetry, etc. , While current laser ablation stages are limited in their ability to implement hexagonal sampling, the benefits of using hexagons can be considered through simulations until hexagonal stages become available.…”