: Electron tomography (ET), an electron-microscopy-based technique that provides three-dimensional (3D) structural information from a tilt series of two-dimensional (2D) projections, has promoted the in-depth investigation of biological molecules in structural biology and the analysis of material structures on the atomic scale in physical sciences. Although ET has developed rapidly as an effective technique wherein atomic-scale resolution has been achieved by using advanced transmission electron microscopy systems, it has not been widely used by the earth and planetary science community. Herein, we verify the applicability of ET in research related to earth and planetary science. The data demonstrate that ET can be used to observe the 3D morphology of mineral grains and 3D distributions of the chemical components of earth and planetary materials. Notably, ET coupled with spectroscopy, including electron energy loss spectroscopy and energy dispersive spectroscopy, is an effective technique for studying the 3D distribution
{"title":"Three-Dimensional Analyses Of Geological Materials On Nanoscale By Electron Tomography","authors":"Jianxi Zhu","doi":"10.46770/as.2022.012","DOIUrl":"https://doi.org/10.46770/as.2022.012","url":null,"abstract":": Electron tomography (ET), an electron-microscopy-based technique that provides three-dimensional (3D) structural information from a tilt series of two-dimensional (2D) projections, has promoted the in-depth investigation of biological molecules in structural biology and the analysis of material structures on the atomic scale in physical sciences. Although ET has developed rapidly as an effective technique wherein atomic-scale resolution has been achieved by using advanced transmission electron microscopy systems, it has not been widely used by the earth and planetary science community. Herein, we verify the applicability of ET in research related to earth and planetary science. The data demonstrate that ET can be used to observe the 3D morphology of mineral grains and 3D distributions of the chemical components of earth and planetary materials. Notably, ET coupled with spectroscopy, including electron energy loss spectroscopy and energy dispersive spectroscopy, is an effective technique for studying the 3D distribution","PeriodicalId":8642,"journal":{"name":"Atomic Spectroscopy","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2022-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48786727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: Olivine is the most abundant mineral in the planetary mantle. Its water content provides critical constraints on the processes and dynamics of the planetary interior. Olivine usually develops zonings with typical widths of 5–20 μm, which requires high spatial resolution. For secondary ion mass spectrometry (SIMS) measurements, primary beams with low currents were utilized to achieve high spatial resolution. However, this strategy also resulted in high background, which cannot be applied to nominally anhydrous minerals, e.g., olivine. Therefore, achieving high spatial resolution with low background is essential but challenging. For example, even though the NanoSIMS is designed for high-spatial-resolution measurements, the spatial resolution remained at > 10 μm for water content analysis in order to maintain a low water background of < 10 ppm. In this study, we optimized the primary beam settings and raster size for water content analysis of olivine using a CAMECA NanoSIMS 50L to improve the spatial resolution and the background simultaneously. Olivine standard samples (KLB-1, ICH-30, Mongok) with a water content ranging from 11.2 ppm to 70.6 ppm were measured for water content calibration with 1 H - / 16 O - ratio. ppm was used for background monitoring. The results showed that a spatial resolution of ~6 μm (primary beam size + raster size) with a background of 6 ± 2 ppm could be achieved by applying a Cs + beam current of 2 nA with a diameter of ~2 μm, rastering an area of 4 × 4 μm 2 . The analytical reproducibility of this method is better than 13% for standard samples with a water content of > 10 ppm. Overall, this method improved the spatial resolution for measuring water content by a factor of ~2 (in comparison to previous studies) and could be applied to olivine grains with complex zoning.
{"title":"High-Spatial-Resolution Measurement Of Water Content In Olivine Using NanoSIMS 50L","authors":"J. Hao, Wei‐Chieh Yang","doi":"10.46770/as.2022.005","DOIUrl":"https://doi.org/10.46770/as.2022.005","url":null,"abstract":": Olivine is the most abundant mineral in the planetary mantle. Its water content provides critical constraints on the processes and dynamics of the planetary interior. Olivine usually develops zonings with typical widths of 5–20 μm, which requires high spatial resolution. For secondary ion mass spectrometry (SIMS) measurements, primary beams with low currents were utilized to achieve high spatial resolution. However, this strategy also resulted in high background, which cannot be applied to nominally anhydrous minerals, e.g., olivine. Therefore, achieving high spatial resolution with low background is essential but challenging. For example, even though the NanoSIMS is designed for high-spatial-resolution measurements, the spatial resolution remained at > 10 μm for water content analysis in order to maintain a low water background of < 10 ppm. In this study, we optimized the primary beam settings and raster size for water content analysis of olivine using a CAMECA NanoSIMS 50L to improve the spatial resolution and the background simultaneously. Olivine standard samples (KLB-1, ICH-30, Mongok) with a water content ranging from 11.2 ppm to 70.6 ppm were measured for water content calibration with 1 H - / 16 O - ratio. ppm was used for background monitoring. The results showed that a spatial resolution of ~6 μm (primary beam size + raster size) with a background of 6 ± 2 ppm could be achieved by applying a Cs + beam current of 2 nA with a diameter of ~2 μm, rastering an area of 4 × 4 μm 2 . The analytical reproducibility of this method is better than 13% for standard samples with a water content of > 10 ppm. Overall, this method improved the spatial resolution for measuring water content by a factor of ~2 (in comparison to previous studies) and could be applied to olivine grains with complex zoning.","PeriodicalId":8642,"journal":{"name":"Atomic Spectroscopy","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49250524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: Glass or amorphous state materials are vital components of lunar regolith and have attracted considerable attention. The analytical data on the texture and structure of glassy and crystallized materials can be used to reconstruct the geological history of the Moon. However, it is often challenging to distinguish glass from crystals based on morphology and elemental composition, especially in complex extraterrestrial samples that have been subjected to significant impact and metamorphism. In this study, micro-X-ray diffraction (µXRD) techniques were used to identify crystalline minerals and glassy phases in lunar breccia samples extracted in the Chang'e-5 mission. The samples were processed using different operating methods to identify a technique that would minimize damage to their original appearance and structure and yield optimal results. The diffraction results, which possessed two-dimensional patterns were classified into dominant dispersion halos, concentric diffraction rings, independent diffraction spots, and coexisting rings and spots. The results correspond to four types of sample states, namely, the amorphous material, polycrystal, single crystal, and a mixture of polycrystals and single crystals. By identifying the crystallization state and phases of various samples in a non-destructive and intuitive manner, µXRD can facilitate in situ analysis of special samples generated during important geological events, thereby promoting the understanding of complex origins and evolution of extraterrestrial bodies.
{"title":"In Situ Micro-XRD Methods For Identifying Glass And Minerals In Extraterrestrial Samples","authors":"Lingya Ma","doi":"10.46770/as.2022.016","DOIUrl":"https://doi.org/10.46770/as.2022.016","url":null,"abstract":": Glass or amorphous state materials are vital components of lunar regolith and have attracted considerable attention. The analytical data on the texture and structure of glassy and crystallized materials can be used to reconstruct the geological history of the Moon. However, it is often challenging to distinguish glass from crystals based on morphology and elemental composition, especially in complex extraterrestrial samples that have been subjected to significant impact and metamorphism. In this study, micro-X-ray diffraction (µXRD) techniques were used to identify crystalline minerals and glassy phases in lunar breccia samples extracted in the Chang'e-5 mission. The samples were processed using different operating methods to identify a technique that would minimize damage to their original appearance and structure and yield optimal results. The diffraction results, which possessed two-dimensional patterns were classified into dominant dispersion halos, concentric diffraction rings, independent diffraction spots, and coexisting rings and spots. The results correspond to four types of sample states, namely, the amorphous material, polycrystal, single crystal, and a mixture of polycrystals and single crystals. By identifying the crystallization state and phases of various samples in a non-destructive and intuitive manner, µXRD can facilitate in situ analysis of special samples generated during important geological events, thereby promoting the understanding of complex origins and evolution of extraterrestrial bodies.","PeriodicalId":8642,"journal":{"name":"Atomic Spectroscopy","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48072824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The adhesion properties of lunar dust grains are a key to determine its motion state. Atomic force microscopy (AFM) is conducted to evaluate the adhesion properties of such ultrasmall grains. However, effective method to measure the adhesion properties of lunar grains has not yet been developed because of the difficulties in eliminating the effect of adsorption of water and gases on the grain surface. In this study, an improved method was proposed to measure the adhesion force of grains while effectively eliminating the gas molecule adsorption effect. In the proposed method, using a focused ion beam, a small grain was mounted onto the tip of an AFM probe and used to measure the adhesion force of the grain. To determine the effects of environmental pressure and temperature, the adhesion force between a silica ball and a silica wafer was measured under different conditions. Based on the results, the gas molecule adsorption effect can be effectively eliminated during adhesion force measurement through AFM at a temperature of 200 °C and an environmental pressure of <2.4 ×10 Pa, at which strong adhesion of the grain is achieved. The proposed method is suitable for the measurement of adhesion force in lunar grain samples.
{"title":"An Improved Method Of Adhesion Force Measurement By Atomic Force Microscopy (AFM)","authors":"Xiongyao Li","doi":"10.46770/as.2022.011","DOIUrl":"https://doi.org/10.46770/as.2022.011","url":null,"abstract":"The adhesion properties of lunar dust grains are a key to determine its motion state. Atomic force microscopy (AFM) is conducted to evaluate the adhesion properties of such ultrasmall grains. However, effective method to measure the adhesion properties of lunar grains has not yet been developed because of the difficulties in eliminating the effect of adsorption of water and gases on the grain surface. In this study, an improved method was proposed to measure the adhesion force of grains while effectively eliminating the gas molecule adsorption effect. In the proposed method, using a focused ion beam, a small grain was mounted onto the tip of an AFM probe and used to measure the adhesion force of the grain. To determine the effects of environmental pressure and temperature, the adhesion force between a silica ball and a silica wafer was measured under different conditions. Based on the results, the gas molecule adsorption effect can be effectively eliminated during adhesion force measurement through AFM at a temperature of 200 °C and an environmental pressure of <2.4 ×10 Pa, at which strong adhesion of the grain is achieved. The proposed method is suitable for the measurement of adhesion force in lunar grain samples.","PeriodicalId":8642,"journal":{"name":"Atomic Spectroscopy","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70586946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cadmium isotope fractionation is a promising indicator for tracing the source, transport, and transformation of Cd in the environment; therefore, a high-precision method for the Cd isotope analysis of environmental samples is urgently required. In this study, eight environmental reference materials (NIST 2711a, GSS-1, GSS-4, GSS-5, GSD-11, GSD-12, GSD-30, and BCR679) with different matrices were digested under microwave irradiation and purified via anion exchange. Thereafter, their Cd isotope ratios were analyzed using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) with double-spike correction. The samples digested under microwave irradiation exhibited high Cd recovery (> 96%). One step of anion-exchangebased purification can remove most interfering elements without any detectable loss of Cd. If the purified solution contained Zn/Cd > 0.04, Zr/Cd > 0.01, Mo/Cd > 0.2, Pd/Cd > 4 × 10, In/Cd > 0.02, or Sn/Cd > 0.1, a secondary step using the same purification procedure would be necessary. The measured δCd values of reference materials (from −0.558 to 0.550‰) were in adequate agreement with those of previous studies, suggesting that this method can be used to analyze the Cd isotope ratios in soil, sediment, and plant samples. In addition, the large variation in the Cd isotope ratios of these reference materials implies that the Cd isotope ratio is promising for identifying pollution sources and the biogeochemical cycle of Cd.
{"title":"Cadmium Isotope Analysis Of Environmental Reference Materials Via Microwave Digestion–Resin Purification–Double-Spike MC-ICP-MS","authors":"Yongguang Yin, Yong Liang","doi":"10.46770/as.2021.1109","DOIUrl":"https://doi.org/10.46770/as.2021.1109","url":null,"abstract":"Cadmium isotope fractionation is a promising indicator for tracing the source, transport, and transformation of Cd in the environment; therefore, a high-precision method for the Cd isotope analysis of environmental samples is urgently required. In this study, eight environmental reference materials (NIST 2711a, GSS-1, GSS-4, GSS-5, GSD-11, GSD-12, GSD-30, and BCR679) with different matrices were digested under microwave irradiation and purified via anion exchange. Thereafter, their Cd isotope ratios were analyzed using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) with double-spike correction. The samples digested under microwave irradiation exhibited high Cd recovery (> 96%). One step of anion-exchangebased purification can remove most interfering elements without any detectable loss of Cd. If the purified solution contained Zn/Cd > 0.04, Zr/Cd > 0.01, Mo/Cd > 0.2, Pd/Cd > 4 × 10, In/Cd > 0.02, or Sn/Cd > 0.1, a secondary step using the same purification procedure would be necessary. The measured δCd values of reference materials (from −0.558 to 0.550‰) were in adequate agreement with those of previous studies, suggesting that this method can be used to analyze the Cd isotope ratios in soil, sediment, and plant samples. In addition, the large variation in the Cd isotope ratios of these reference materials implies that the Cd isotope ratio is promising for identifying pollution sources and the biogeochemical cycle of Cd.","PeriodicalId":8642,"journal":{"name":"Atomic Spectroscopy","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2022-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42337027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: Plagioclase, pyroxene and glass are the main component phases of different planetary materials. In situ Rb-Sr dating of these common phases thus would represent the timing of magmatic differentiation, effectively complementary to the rare, tiny U-Pb bearing phases that only form at a late stage. In this study, we selected lunar meteorites as examples to establish an i n situ Rb-Sr dating method where plagioclase, pyroxene, ilmenite, and glasses were the laser-ablation (LA) targets. The accuracy of 87 Sr/ 86 Sr and 87 Rb/ 86 Sr measured by LA-MC-ICP-MS was better than 0.2 ‰ and 3 %, respectively, for samples with an 87 Rb/ 86 Sr ratio lower than 1. However, we found that the distributions of Rb and Sr in the natural materials were heterogeneous at the micrometer scale, leading to inaccurate 87 Rb/ 86 Sr ratio correction when calculated by normal data reduction methods. A new data reduction strategy of the smallest unit of isochron age (SUIA) was developed. Using the SUIA, the Rb-Sr isochron age of 2984 ± 43 Ma and 3149 ± 20 Ma was obtained for two lunar meteorites (NWA 10597 and NWA 6950, respectively). These results are identical within 1-2% deviation relative to the U-Pb dating ages for baddeleyite and apatite using SIMS. The present method may have broad applicability for determining the Rb-Sr isochron ages of other planetary samples.
{"title":"In Situ Rb-Sr Dating Of Lunar Meteorites Using Laser Ablation MC-ICP-MS","authors":"Wen Zhang","doi":"10.46770/as.2022.007","DOIUrl":"https://doi.org/10.46770/as.2022.007","url":null,"abstract":": Plagioclase, pyroxene and glass are the main component phases of different planetary materials. In situ Rb-Sr dating of these common phases thus would represent the timing of magmatic differentiation, effectively complementary to the rare, tiny U-Pb bearing phases that only form at a late stage. In this study, we selected lunar meteorites as examples to establish an i n situ Rb-Sr dating method where plagioclase, pyroxene, ilmenite, and glasses were the laser-ablation (LA) targets. The accuracy of 87 Sr/ 86 Sr and 87 Rb/ 86 Sr measured by LA-MC-ICP-MS was better than 0.2 ‰ and 3 %, respectively, for samples with an 87 Rb/ 86 Sr ratio lower than 1. However, we found that the distributions of Rb and Sr in the natural materials were heterogeneous at the micrometer scale, leading to inaccurate 87 Rb/ 86 Sr ratio correction when calculated by normal data reduction methods. A new data reduction strategy of the smallest unit of isochron age (SUIA) was developed. Using the SUIA, the Rb-Sr isochron age of 2984 ± 43 Ma and 3149 ± 20 Ma was obtained for two lunar meteorites (NWA 10597 and NWA 6950, respectively). These results are identical within 1-2% deviation relative to the U-Pb dating ages for baddeleyite and apatite using SIMS. The present method may have broad applicability for determining the Rb-Sr isochron ages of other planetary samples.","PeriodicalId":8642,"journal":{"name":"Atomic Spectroscopy","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2022-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48544969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: As the Chinese lunar exploration project prepares for future exploration activities on the Moon, there is a growing need to develop high-fidelity lunar soil simulants. The morphological analysis of lunar soil and its simulant is important for matching the unique properties of the agglutinates. To date, several techniques, including scanning electron, X-ray, and optical microscopies, have been extensively applied to analyze the three-dimensional (3D) morphology of lunar samples. However, none of these tools can acquire the natural color fine 3D microstructure of the samples, which is necessary to analyze components of the lunar meteorite and soil particles. In this letter, we present a high-resolution, natural color 3D tomographic system for the initial analysis of lunar samples. The superior performance of the system is demonstrated by the fine details and color 3D tomography of a lunar meteorite and lunar soil simulant. This method is expected to provide an essential tool for visually presenting the geological evolution of the Moon.
{"title":"Reconstructing The Color 3D Tomography Of Lunar Samples","authors":"M. Lei","doi":"10.46770/as.2022.009","DOIUrl":"https://doi.org/10.46770/as.2022.009","url":null,"abstract":": As the Chinese lunar exploration project prepares for future exploration activities on the Moon, there is a growing need to develop high-fidelity lunar soil simulants. The morphological analysis of lunar soil and its simulant is important for matching the unique properties of the agglutinates. To date, several techniques, including scanning electron, X-ray, and optical microscopies, have been extensively applied to analyze the three-dimensional (3D) morphology of lunar samples. However, none of these tools can acquire the natural color fine 3D microstructure of the samples, which is necessary to analyze components of the lunar meteorite and soil particles. In this letter, we present a high-resolution, natural color 3D tomographic system for the initial analysis of lunar samples. The superior performance of the system is demonstrated by the fine details and color 3D tomography of a lunar meteorite and lunar soil simulant. This method is expected to provide an essential tool for visually presenting the geological evolution of the Moon.","PeriodicalId":8642,"journal":{"name":"Atomic Spectroscopy","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2022-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49262069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: Synchrotron-based scanning transmission X-ray microscopy (STXM) efficiently integrates X-ray microscopy and X-ray absorption spectroscopy (XAS) to provide quantitative, chemically specific imaging of elements, functional groups, bonding, and oxidation states in 2D and 3D modes at high spatial resolution (sub-10 to 30 nm), high energy resolution, and low radiation doses. STXM has been increasingly used to study various materials and samples for life, earth, planetary, and environmental sciences. In this progress report and minireview, the STXM principle and instrumentation of conventional STXM and the latest STXM-ptychography at the Canadian Light Source are first discussed. Then, two representative applications of STXM on geoscience-related samples, including magnetotactic bacteria, soil microaggregates, and related systems, are presented to illustrate the strong capabilities and suitability of STXM to elucidate complex systems, processes, and associations in the natural sciences. Finally, the potential applications and prospects of the STXM-related techniques in characterizing precious extraterrestrial samples ( e.g. , lunar samples returned by China’s Chang’e-5 mission) are briefly discussed.
{"title":"Scanning Transmission X-Ray Microscopy At The Canadian Light Source: Progress And Selected Applications In Geosciences","authors":"Jian Wang, Jinhui Li","doi":"10.46770/as.2022.008","DOIUrl":"https://doi.org/10.46770/as.2022.008","url":null,"abstract":": Synchrotron-based scanning transmission X-ray microscopy (STXM) efficiently integrates X-ray microscopy and X-ray absorption spectroscopy (XAS) to provide quantitative, chemically specific imaging of elements, functional groups, bonding, and oxidation states in 2D and 3D modes at high spatial resolution (sub-10 to 30 nm), high energy resolution, and low radiation doses. STXM has been increasingly used to study various materials and samples for life, earth, planetary, and environmental sciences. In this progress report and minireview, the STXM principle and instrumentation of conventional STXM and the latest STXM-ptychography at the Canadian Light Source are first discussed. Then, two representative applications of STXM on geoscience-related samples, including magnetotactic bacteria, soil microaggregates, and related systems, are presented to illustrate the strong capabilities and suitability of STXM to elucidate complex systems, processes, and associations in the natural sciences. Finally, the potential applications and prospects of the STXM-related techniques in characterizing precious extraterrestrial samples ( e.g. , lunar samples returned by China’s Chang’e-5 mission) are briefly discussed.","PeriodicalId":8642,"journal":{"name":"Atomic Spectroscopy","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2022-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44922256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: Nanophase iron (np-Fe 0 ) is a major product of space weathering and its presence significantly alters the reflectance spectral characteristics of lunar soil. Previous studies have established that the np-Fe 0 particles originate from the reduction of ferrous ions in the plasma, in-situ decomposition of olivine and pyroxene, and disproportionation of ferrous ions in solid ferrosilicates. In this study, sample charging effects were eliminated and in situ nanoscale valence state analysis of iron-bearing phases in Chang’E-5 lunar soil was conducted by combining focused ion beam (FIB) microscopy, Auger electron spectroscopy (AES), and transmission electron microscopy-electron energy loss spectroscopy (TEM-EELS) techniques. The results indicate that the contents and valence states of iron in the np-Fe 0 particles, amorphous matrix, and ferrosilicates differ. The np-Fe 0 particles were found to be composed of pure metallic iron, whereas ferrous and ferric iron ions were present in olivine crystals and the amorphous matrix, respectively. The discovery of both metallic and ferric iron in the amorphous matrix of Chang’E-5 lunar soil offers new insights regarding the disproportionation reaction of Fe 2+ on the lunar surface. This study demonstrates that the combination of FIB, AES, and TEM-EELS is an effective and precise approach for analyzing the valence states of iron-bearing phases in lunar soil, which can be extended to other extraterrestrial samples and other multivalent elements.
纳米相铁(np- fe0)是空间风化的主要产物，它的存在显著改变了月球土壤的反射率光谱特征。先前的研究已经确定，np-Fe 0颗粒来源于等离子体中亚铁离子的还原、橄榄石和辉石的原位分解以及固体硅铁中亚铁离子的歧化。在消除样品电荷效应的基础上，结合聚焦离子束(FIB)显微镜、俄歇电子能谱(AES)和透射电子能谱(TEM-EELS)技术，对嫦娥五号月球土壤中含铁相进行了原位纳米价态分析。结果表明，nfp - fe 0颗粒、非晶基体和硅酸铁中铁的含量和价态不同。发现np- fe0颗粒由纯金属铁组成，而亚铁和三铁离子分别存在于橄榄石晶体和非晶基体中。在“嫦娥五号”月壤非晶态基质中同时发现金属铁和铁离子，为研究月球表面Fe 2+的歧化反应提供了新的思路。研究结果表明，FIB、AES和TEM-EELS相结合是一种有效、精确的月壤含铁相价态分析方法，可推广到其他地外样品和其他多价元素中。
{"title":"In Situ Investigation Of The Valence States Of Iron-Bearing Phases In Chang’E-5 Lunar Soil Using FIB, AES, And TEM-EELS Techniques","authors":"Yang Li","doi":"10.46770/as.2022.002","DOIUrl":"https://doi.org/10.46770/as.2022.002","url":null,"abstract":": Nanophase iron (np-Fe 0 ) is a major product of space weathering and its presence significantly alters the reflectance spectral characteristics of lunar soil. Previous studies have established that the np-Fe 0 particles originate from the reduction of ferrous ions in the plasma, in-situ decomposition of olivine and pyroxene, and disproportionation of ferrous ions in solid ferrosilicates. In this study, sample charging effects were eliminated and in situ nanoscale valence state analysis of iron-bearing phases in Chang’E-5 lunar soil was conducted by combining focused ion beam (FIB) microscopy, Auger electron spectroscopy (AES), and transmission electron microscopy-electron energy loss spectroscopy (TEM-EELS) techniques. The results indicate that the contents and valence states of iron in the np-Fe 0 particles, amorphous matrix, and ferrosilicates differ. The np-Fe 0 particles were found to be composed of pure metallic iron, whereas ferrous and ferric iron ions were present in olivine crystals and the amorphous matrix, respectively. The discovery of both metallic and ferric iron in the amorphous matrix of Chang’E-5 lunar soil offers new insights regarding the disproportionation reaction of Fe 2+ on the lunar surface. This study demonstrates that the combination of FIB, AES, and TEM-EELS is an effective and precise approach for analyzing the valence states of iron-bearing phases in lunar soil, which can be extended to other extraterrestrial samples and other multivalent elements.","PeriodicalId":8642,"journal":{"name":"Atomic Spectroscopy","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2022-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48620449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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