Nanosecond Laser Ablation of Ti–6Al–4V under Different Temperature

Multi-pulse nanosecond laser ablation of Ti–6Al–4V is a complex process. In this study, the effect of substrate temperature on the nanosecond laser ablation of Ti–6Al–4V was investigated. Morphology, diameter and depth of ablation craters were observed; ablation efficiency ω (μm3/mJ) was proposed to analyzes the ablation process. The results showed that, with the increasing of substrate temperature, the ablation craters’ diameter increased and depth decreased, while ω initially increased, but then decreased rapidly. Furthermore, with increasing pulse number, the depth of ablation crater increased linearly, while the growth of the diameter gradually slowed down and tended to be stable after the 16th irradiation. The above changes were different in details at different substrate temperatures.

Evaluating the reliability of U–Pb laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) carbonate geochronology: matrix issues and a potential calcite validation reference material

We document that the reliability of carbonate U–Pb dating by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is improved by matching the aspect ratio of the LA single-hole drilling craters and propagating long-term excess variance and systematic uncertainties. We investigated the impact of different matrices and ablation crater geometries using U–Pb isotope analyses of one primary (WC-1) and two secondary reference materials (RMs). Validation RMs (VRMs) include a previously characterised one (ASH-15D) and a new candidate (JT), characterised by ID-TIMS (intercept age: 13.797±0.031 Ma) with excellent agreement to pooled LA-ICP-MS measurements (13.75±0.11 | 0.36 Ma), a U concentration of approx. 1 µg g−1 and 238U∕206Pb ratios from 5 to 460, defining the isochron well. Differences in ablation crater depth to diameter ratios (aspect ratio) introduce an offset due to downhole fractionation and/or matrix effects. This effect can be observed either when the crater size between U–Pb RM and the sample changes or when the ablation rate for the sample is different than for the RM. Observed deviations are up to 20 % of the final intercept age depending on the degree of crater geometry mismatch. The long-term excess uncertainty was calculated to be in the range of 2 % (ASH-15D) to 2.5 % (JT), and we recommend propagating this uncertainty into the uncertainty of the final results. Additionally, a systematic offset to the ID-TIMS age of 2 %–3 % was observed for ASH-15D but not for JT. This offset might be due to different ablation rates of ASH-15D compared to the primary RM or remaining matrix effects, even when the aspect ratios chosen are similar.

New analytical and data evaluation protocols to improve the reliability of U-Pb LA-ICP-MS carbonate dating

We document that the reliability of carbonate U-Pb dating by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is improved by matching the aspect ratio of the LA single hole drilling craters and propagating of long-term excess uncertainty and systematic uncertainties. We investigated the impact of different matrices and ablation crater geometries using U-Pb isotope analyses of one primary (WC-1) and two secondary reference materials (RMs). Validation RMs (VRM) include a previously characterized (ASH-15D) and a new candidate (JT), characterized by ID-TIMS (intercept age: 13.797 ± 0.031 Ma) with excellent agreement to pooled LA-ICP-MS measurements (13.81 ± 0.11 ¦ 0.30 Ma), U concentration of approx. 1 μg/g and 238U/206Pb ratios from 5 to 460, well defining the isochron. Differences in ablation crater depth to diameter ratios (aspect ratio) introduce an offset due to downhole fractionation and/or matrix effects. This effect can be observed either when the crater size between U-Pb RM and sample changes or when the ablation rate for the sample is different than for the RM. Observed deviations are up to 20 % of the final intercept age depending on the degree of crater geometry mismatch. The long-term excess uncertainty was calculated to be in the range of 2 % (ASH-15D) to 2.5 % (JT), and we recommend propagating this uncertainty into the uncertainty of the final results. Additionally, a systematic offset to the ID-TIMS age of 2–3 % was observed for ASH-15D but not for JT. This offset might be due to different ablation rates of ASH-15D compared to the primary RM or remaining matrix effects, even when chosen aspect ratios are similar.

The effect of sample surface roughness on the microanalysis of microchip laser-induced breakdown spectroscopy

In the microanalysis of laser-induced breakdown spectroscopy, the influence of surface roughness on spectral stability and quantitative analysis capability was studied for the first time when the laser ablation crater diameter was approximately 10 μm.

Ablation Characteristics of Nanosecond Laser Pulsed Ablation of Aluminum

This research presents laser ablation characteristics of an aluminum alloy after nanosecond pulsed laser ablation (PLA) with a 1064 nm Nd:YAG laser. White light interferometry and scanning electron microscopy were used to establish relationships between laser ablation characteristics and the number of pulses at different beam energies. Laser ablation features studied in this research are crater profiles, radii and depth, and extent of surface damage. An extensive damaged area around the laser ablation crater was found and is believed to be produced by the laser-induced plasma generated during PLA. Spectroscopic analysis showed that there is a correlation between the plasma formation threshold and the initiation of the plasma-affected area, and laser ablation at different angles of incidence between the beam and the sample showed a correlation between the plasma shape and the shape of the damaged area around the ablation crater. However, the variables influencing the occurrence of the plasma-affected and the extent of plasma-induced damage are not yet fully recognized and understood.

Investigation on the suitability of ablated carbon as an internal standard in laser ablation ICP-MS of polymers

The ablation crater shapes and the correlation between ablated carbon and 13C-ICP-MS signals of twenty-one virgin polymers with laser ablation were investigated.

Ultrafast Dynamics of Sub-Wavelength Periodic Surface Structuring during Femtosecond Laser Processing of Dielectrics

A femtosecond laser pulse duration is shorter than many physical/chemical characteristic times, which makes it possible to control electron dynamics such as ionizations and electron densities. This study expermetally investigtes the effects of laser fluence on sub-wavelength periodic surface structuring based on ultrafast laser electron dynamics control. A quantum model for the sub-wavelength periodic surface structuring is also proposed, which considers both the wave properties in the photon particle-properties based plasma model for photon-electron interactions and transient localized changes of material properties. It shows that the laser fluence strongly affects the ablation crater shapes. The prediction of ablation crater shape and periodicity is in agreement with experimental data.