Abstract:

Abstract:The Terracotta Warriors, one of the most remarkable archaeological discoveries of the 20th century, provide critical insights into the artistic, technological, and military achievements of the Qin Dynasty. This study established a micro-area quantitative and imaging analysis method for the Qin Terracotta Warriors using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Matrix-matched calibration standards were produced using the powder–pellet method, thereby ensuring the reliable quantification of both major and trace elements. Optimized ablation parameters (energy density of 8.3 J cm?2, repetition rate of 20 Hz, and spot size of 100 μm) yielded stable signal intensities with relative standard deviations below 10%. The application of this method to multiple fragments of the Terracotta Warriors revealed compositional variations associated with color differences, structural layering, and excavation contexts. Quantitative accuracy ranged from 80% to 120%, and elemental imaging was achieved at a spatial resolution of 100 μm. High-resolution multielement maps illustrated the heterogeneous distributions of Cu, As, and Co linked to the pigment residues, offering new insights into pigment preparation techniques and post-burial alteration processes. Overall, the results demonstrate that LA-ICP-MS is a minimally destructive and high-resolution analytical tool that is well suited for the compositional and technological investigation of archaeological ceramics.

Abstract:Magnesium (Mg) isotopic compositions help decode the complex biogeochemical cycling of Mg in surficial environments. Accurate measurement of Mg isotopes in biological samples requires reference materials with established isotopic compositions, which ensure analytical quality and allow interlaboratory comparison. By employing Nu Plasma III multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS), this study establishes a high-precision Mg isotopic dataset for sixteen biological reference materials. The measured δ26Mg values of extra nine reference materials (plant leaves, rocks, and seawater) consistently agree well with references values, confirming the reliability of analytical methodology used in this study. The results reveal the variations for δ26Mg values exceeding 2.2‰ across the food web. Plant leaves are characterized by low δ26Mg values (–0.52‰ ± 0.04‰ ~ –1.28‰ ± 0.03‰), whereas cereals and animal organs exhibit heavier values (up to 0.97‰ ± 0.05‰ for pork liver). The δ26Mg values of scallops (GSB-15), spirulina (GSB-16), and prawn (GSB-28) cluster together with lighter values, representing a marine-derived isotopic end-member for coastal populations. Human hairs (–0.88‰ ± 0.04‰) present an integrated isotopic signature intermediate between major dietary end-members. This dataset expands the Mg isotopic compositions of major dietary and human tissue reference materials, supporting the essential laboratory comparison of isotope analyses and facilitating researches into the Mg biogeochemical cycle.

Abstract:Laser energy fluctuations, focal plane position errors, and sample matrix variations are major sources of uncertainty in Laser-Induced Breakdown Spectroscopy (LIBS). A systematic investigation of plasma characteristics under varying laser energies, focal positions, and sample matrices is essential for understanding plasma evolution and the mechanisms underlying measurement uncertainty. Although radiation evolution directly reflects plasma dynamics, its response to these factors remains insufficiently explored. In this study, we experimentally monitored radiation evolution under different laser energies, focal plane positions, and sample matrices, revealing a consistent bimodal pattern: the first peak, dominated by background radiation, exhibited a pulsed profile, while the second peak, governed by excited-state de-excitation radiation, followed a log-normal distribution. The onset time, intensity, and decay rate of the second peak varied across conditions, reflecting inherent uncertainty in LIBS radiation evolution. By integrating multi-wavelength radiation data, spectroscopic measurements, ablation crater volumes, and plasma parameters, we found that higher initial plasma temperatures delayed the second peak, higher initial total population densities increased its intensity, and the decay after the second peak was jointly influenced by the initial electron density and ionization level. These findings provide direct evidence for the dynamic evolution mechanisms of laser-induced plasmas and offer insights for refining temporal plasma models, optimizing LIBS acquisition strategies, and enhancing measurement stability and precision.

Abstract:Vesuvianite is a prevalent mineral in skarn system and has become an indispensable U-Pb geochronometer due to its capable of directly constraining the timing of skarn mineralization. However, the matrix effects between various potential primary reference materials and vesuvianite are not yet fully understood. This study evaluates four potential reference materials: vesuvianite Wilui, garnet PL57, garnet Willsboro, and zircon 91500, for vesuvianite U-Pb dating. The results indicate that the matrix effect between Wilui and other vesuvianite samples is negligible under different ablation conditions. In contrast, PL57 exhibits a pronounced matrix effect under most analytical conditions, limiting its application as an external calibrator for U-Pb dating of vesuvianite. Both Willsboro and 91500 show insignificant matrix effect with vesuvianite at a repetition rate of 5 Hz and fluence of 3 J/cm2, across a range of spot sizes (16–44 μm). Moreover, 91500 is suitable for use with spot size ranging from 32 to 44 μm, when combined with either 10 Hz - 3 J/cm2 or 5 Hz - 5 J/cm2. Consequently, 91500 emerges as more suitable non-matrix-matched reference material in light of its high homogeneity and wide applicability. Furthermore, this study successfully and precisely determined the trace elements and U-Pb age of vesuvianite samples Bufa and M6635 using four reference materials as external calibrators at condition of 44 μm - 5 Hz - 3 J/cm2. The obtained U-Pb ages of 30–33 Ma and 225–233 Ma are in good agreement with their ID-TIMS ages within the measurement errors, respectively. This demonstrates the reliability and feasibility of the optimized calibration methods employed in this study.

Abstract:This study investigated the use of n-type SiC substrates as mask materials for the depth profiling of p-type SiC epitaxial wafers using GD-MS. The optimized glow discharge conditions for achieving a flat crater and effective signal intensity were a discharge current of 2 mA and a discharge voltage of 1000 V. The epitaxial layers prepared by chemical vapor deposition were tested, and the results demonstrated that the mask technique effectively reduced edge effects and improved the sputter crater morphology. The optimal mask conditions were a thickness of 0.35 mm with a 4 mm aperture, achieving a depth resolution of 56 nm. The accuracy and reliability of the mask technique were validated using epitaxial wafers with known doping concentrations, showing a 5% deviation from the actual values. This study provides an efficient and reliable method for determining the elemental concentration and distribution in semiconductor epitaxial layers by GD-MS.

Abstract:Determination of lithium was conducted by standard addition and isotope dilution, where lithium isotopes were measured by tandem quadrupole inductively coupled plasma mass spectrometry (ICP-QMS/QMS). Considering the low atomic mass of lithium, the ICP-QMS/QMS operating conditions were optimized to minimize the suppression of signal intensities due to space charge effects. Attentions were also paid to spectral interferences affecting the measurements of lithium isotopes, for which the results showed oxygen reaction help reduce related spectral interferences while lithium isotopes were measured at on-mass mode. Lower radio frequency (RF) power at 700 W provided lower background equivalent concentrations for lithium isotopes but higher RF power at 1600 W resulted in higher reliable results of lithium isotopic ratio. Lithium in multiple seawater certified reference materials (CRMs) were determined by both standard addition at lower RF power condition and isotope dilution at higher RF power condition, showing lithium concentration in the range of 150 ng/g to 170 ng/g. The results obtained by standard addition and isotope dilution were in coincidence with each other for each seawater CRM sample, confirming the reliability of these results.

Abstract:Fiber-laser-based laser-induced breakdown spectroscopy (FL-LIBS) is well suited for in-situ and rapid analysis of thermal aging steels in nuclear power systems. The unique ablation behavior of the fiber laser strongly affects plasma excitation and spectral characteristics. This study aims to investigate how ablation features influence plasma excitation and emission characteristics in the FL-LIBS process. Different ablation modes were obtained by adjusting the focal position and power density. The ablation process was characterized through crater morphology analysis and the observation of phase explosion. These results were then correlated with plasma excitation behavior. At -2mm, the laser heating efficiency reached its highest level. This allowed the plasma temperature to remain high even at low power densities. Under this condition, the spectral quality was the best, with high signal-to-noise ratio (SNR) and low relative standard deviation (RSD). At +2mm, stronger ablation was achieved at the expense of excessive ionization. The accompanying increase in bremsstrahlung emission suppressed the spectral SNR. Under both ±2mm settings, higher power density drove the ablation mode from vaporization to phase explosion. The generated vapor–droplet mixture modified the plasma excitation behavior. At 0mm, the slower decay of edge energy strengthened heat conduction around the core-ablation zone. This effect led to an expansion of the thermal-conduction zone. At high power levels, such expansion intensified pulse-to-pulse thermal interference, resulting in reduced ablation stability and a more dispersed plasma excitation distribution. These findings provide a physical basis for optimizing the FL-LIBS system and guide accurate in-situ thermal aging diagnostics of nuclear power plant steel.

Abstract:The fragile Antarctic ecosystem is now more threatened by anthropogenic impacts than ever before, particularly in maritime Antarctica. Technology-critical elements (TCEs) produced by industrial activities can reach Antarctica by long-range atmospheric transport. This study aimed to determine the contents of indium, thallium, antimony, and bismuth in lichens from Deception Island, King George Island, Livingston Island, Nelson Island, Horseshoe Island, and James Ross Island, in order to identify potential contaminants. An analytical method employing high-resolution continuum source hydride generation atomic absorption spectrometry (HR-CS HGAAS) with a detection limit of 0.002 mg kg-1 was developed for the precise determination of bismuth. The highest observed contents of In, Tl, Sb, and Bi were 0.44 mg kg-1, 0.018 mg?kg-1, 0.257 mg kg-1, and 0.011 mg?kg-1, respectively. Knowing the current state of metal levels in this area is important for further research owing to the minimal clarification of the deposition and fate of TCEs in Antarctica.

Abstract:Efficient and precise quantification of rare earth elements (REEs) constitutes a pivotal challenge for advancing extraterrestrial resource exploration. Conventional spectral quantification models typically prioritize isolated characteristic lines, neglecting the analytical potential of full- range spectral data in complex matrices. This research addresses the quantitative determination of trace samarium (Sm) in basaltic matrices through preparation of standardized samples with Sm concentrations spanning 50-140 mg/kg, investigated and optimised the quantitative models based on Laser-Induced Breakdown Spectroscopy (LIBS) combined with Partial Least Squares Regression (PLSR). Although traditional PLSR models demonstrate quantitative feasibility, experimental results revealed that characteristic spectral line models exhibit substantial prediction deviations, while the spectral background contains diagnostically critical information that should be retained for quantitative analysis. The implementation of wavelet transformation (WT) enabled profound extraction of latent features from full-range ultraviolet (UV) spectra. The developed WT-PLSR models demonstrated substantial superiority over traditional full-range UV spectral PLSR models, with the optimal model achieving training set R2 = 0.99929 and test set R2 = 0.9928. This methodology significantly enhanced both predictive precision and model robustness, confirming the critical importance of background information utilization. This provides a novel approach for developing in situ, high-precision spectroscopic quantification techniques for trace REEs in complex matrices.

Abstract:Zinc (Zn) isotopes are increasingly applied in biogeochemistry, nutrition, and environmental sciences, but systematic data for biological reference materials remain scarce. In this study, we present high-precision Zn isotope measurements of a wide range of certified biological reference materials, including plants, animal tissues, human tissues, and processed food, using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) combined with a one-column ion-exchange purification protocol. The analytical procedure yielded excellent repeatability, with long-term precision better than ± 0.07 ‰ (2SD) for δ66/64Zn. Isotopic analyses were performed on 23 certified biological reference materials, covering plants (e.g., wheat, spinach leaves, ginseng), animal/human tissues (e.g., scallop, pork liver, human hair), and processed foods (e.g., milk powder, infant formula). The measured δ66/64Zn values span distinct ranges: plants (0.19‰ to 0.84 ‰), animal tissues (-0.61 ‰ to 0.35 ‰), human hair (-0.07 ‰ to -0.08 ‰), and food products (0.49 ‰ to 0.88 ‰). These results were consistent with previously reported data for selected standards (e.g., BCR-2, BHVO-2, GBW10051), confirming method accuracy. Importantly, this study provides the first systematic dataset of δ66/64Zn values for 18 previously unreported biological reference materials, thereby establishing robust baselines for future research in Zn biogeochemical cycling, food authenticity, nutritional assessment, paleodiet and biomedical applications.

Abstract:Molybdenum (Mo) isotopic analysis using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) has become a cornerstone technique in modern geochemistry. However, achieving accurate and precise measurements in samples with low Mo concentrations or complex matrices remains challenging due to conventional instrument limitations. This study presents the first systematic evaluation of the Thermo Scientific Neoma MS/MS MC-ICP-MS, a new and advanced platform featuring a double-Wien filter and an advanced collision/reaction cell (CRC) design, for Mo isotope measurements. We investigated how instrumental configurations—specifically cone combinations and plasma conditions—affect sensitivity and matrix tolerance, focusing on its potential to overcome existing analytical barriers. Compare to Neptune platform, the Neoma MS/MS exhibits markedly enhanced sensitivity, yielding a 2- to 5-fold improvement, under both dry and wet plasma conditions. Critically, a long-term external precision of 0.06‰ (2SD) at low concentrations, down to 10 ng g-1, was achieved via Neoma. Notably, the Jet/X cone interface simultaneously enhances signal intensity and mitigates matrix effect, successfully challenging the conventional trade-off between sensitivity and matrix effect. These results highlight the Neoma MS/MS as a significant advancement for high-precision Mo isotope analysis, offering unprecedented accuracy and resilience under demanding geological conditions, particularly for samples with extremely low Mo content.