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- 摘要
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Chemical analysis of a lunar meteorite by laser ablation mass spectrometry
摘要： The lunar meteorite Sayh al Uhaymir 169, that contains KREEP rich material, was investigated with our miniature laser ablation time-of-flight mass spectrometer to simulate the expected performance of in-situ measurements on the surface of a planetary body. The abundances of the major elements on the KREEP part of the rock were measured and plotted on a two-dimensional surface map to identify different mineral phases in the sample. The element distribution maps reveal the grain boundaries and allow identification of individual minerals and their major and trace element compositions. In the second measurement campaign the instrument was coupled with a HV pulser to increase sensitivity of the measurements. It could be shown that the detection sensitivity for heavy trace elements can be significantly improved while removing light elements from the analyzed ion beam. This study provides also measurements of U, Th and Pb elements present inside a single zircon grain. With the abundances of U and Pb in the zircon grain a preliminary age estimation of the zircon could be made and was found to be in reasonable agreement with ages reported in literature. Moreover, from the Ti concentration in the zircon grain a crystallization temperature was derived. Thus, by employing such an instrument on a planetary surface, scientific useful in-situ measurements on the element composition, the mineralogy, petrology and dating of surface samples can be accomplished.
关键词： Lunar meteorite,Trace elements,Laser ablation mass spectrometry,Crystallization temperature,KREEP material,Zircon
更新于2025-09-12 10:27:22
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[ACS Symposium Series] Fundamentals and Applications of Phosphorus Nanomaterials Volume 1333 || Phosphorus Clusters and Quantum Dots
摘要： Cluster is characterized by its unique role in chemistry and physics due to the fact that it bridges isolated atoms and bulk counterparts. It is also found that the structures and properties of clusters change dramatically with their sizes. Characterized by its diverse bonding patterns, phosphorus clusters have attracted many interests in past years. With the help of laser ablation mass spectrometry and other relative technologies, many kinds of phosphorus clusters have been generated, identified and studied. Their structures and properties are also widely studied by theoretical calculations. This chapter reviews both experimental and theoretical progresses about phosphorus clusters and relative species. On the other hand, the phosphorus quantum dots have attracted a great deal of attention due to its unique structures, properties, and applications in recent years. A quick overview on this topic is also included in the chapter, in order to attract more interests from broad research fields and make a bridge across the cluster study and nanomaterials to benefit scientists in both fields.
关键词： theoretical calculations,laser ablation mass spectrometry,quantum dots,phosphorus clusters,nanomaterials
更新于2025-09-12 10:27:22
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Tissue classification by rapid evaporative ionization mass spectrometry (REIMS): comparison between a diathermic knife and CO2 laser sampling on classification performance
摘要： The increasing need for rapid, in situ, and robust tissue profiling approaches in the context of intraoperative diagnostics has led to the development of a large number of ambient ionization-based surface sampling strategies. This paper compares the performances of a diathermic knife and a CO2 laser handpiece, both clinically approved, coupled to a rapid evaporative ionization mass spectrometry (REIMS) source for quasi-instantaneous tissue classification. Several fresh meat samples (muscle, liver, bone, bone marrow, cartilage, skin, fat) were obtained from different animals. Overall, the laser produced cleaner cuts and more reproducible and higher spectral quality signals when compared with the diathermic knife (CV laser = 9–12%, CV diathermic = 14–23%). The molecular profiles were subsequently entered into a database and PCA/LDA classification/prediction models were built to assess if the data generated with one sampling modality can be employed to classify the data generated with the other handpiece. We demonstrate that the correct classification rate of the models increases (+ 25%) with the introduction of a model based on peak lists that are tissue-specific and common to the two handpieces, compared with considering solely the whole molecular profile. This renders it possible to use a unique and universal database for quasi-instantaneous tissue recognition which would provide similar classification results independent of the handpiece used. Furthermore, the laser was able to generate aerosols rich in lipids from hard tissues such as bone, bone marrow, and cartilage. Combined, these results demonstrate that REIMS is a valuable and versatile tool for instantaneous identification/classification of hard tissue and coupling to different aerosol-generating handpieces expands its field of application.
关键词： Bioanalytical methods,Tissue analysis,Laser ablation,Mass spectrometry,REIMS,Lipids
更新于2025-09-12 10:27:22