scholarly journals Determining Chemically and Spatially Resolved Atomic Profile of Low Contrast Interface Structure with High Resolution

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Maheswar Nayak ◽  
P. C. Pradhan ◽  
G. S. Lodha ◽  
A. Sokolov ◽  
F. Schäfers

Abstract We present precise measurements of atomic distributions of low electron density contrast at a buried interface using soft x-ray resonant scattering. This approach allows one to construct chemically and spatially highly resolved atomic distribution profile upto several tens of nanometer in a non-destructive and quantitative manner. We demonstrate that the method is sensitive enough to resolve compositional differences of few atomic percent in nano-scaled layered structures of elements with poor electron density differences (0.05%). The present study near the edge of potential impurities in soft x-ray range for low-Z system will stimulate the activity in that field.

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Maheswar Nayak ◽  
P. C. Pradhan ◽  
G. S. Lodha ◽  
A. Sokolov ◽  
F. Schäfers

Author(s):  
Wenbing Yun ◽  
Steve Wang ◽  
David Scott ◽  
Kenneth W. Nill ◽  
Waleed S. Haddad

Abstract A high-resolution table-sized x-ray nanotomography (XRMT) tool has been constructed that shows the promise of nondestructively imaging the internal structure of a full IC stack with a spatial resolution better than 100 nm. Such a tool can be used to detect, localize, and characterize buried defects in the IC. By collecting a set of X-ray projections through the full IC (which may include tens of micrometers of silicon substrate and several layers of Cu interconnects) and applying tomographic reconstruction algorithms to these projections, a 3D volumetric reconstruction can be obtained, and analyzed for defects using 3D visualization software. XRMT is a powerful technique that will find use in failure analysis and IC process development, and may facilitate or supplant investigations using SEM, TEM, and FIB tools, which generally require destructive sample preparation and a vacuum environment.


1998 ◽  
Vol 41-42 ◽  
pp. 275-278 ◽  
Author(s):  
Y. Chen ◽  
G. Simon ◽  
A.M. Haghiri-Gosnet ◽  
L. Manin ◽  
H. Launois
Keyword(s):  

2019 ◽  
Vol 2019 (6) ◽  
pp. 875-884 ◽  
Author(s):  
Maxim G. Chegerev ◽  
Alexandr V. Piskunov ◽  
Kseniya V. Tsys ◽  
Andrey G. Starikov ◽  
Klaus Jurkschat ◽  
...  

2021 ◽  
Author(s):  
Αλέξανδρος Εμμανουηλίδης

This thesis presents a multi-proxy reconstruction from 5 different coastal wetlands of southern Greece spanning in the Holocene period and an in-depth review and application of non-destructive systems (CT scanning, X-ray Fluorescence) in paleoenvironmental research. During this thesis, the acquired dataset used consisted of a) X-ray Fluorescence scanning (XRF), b) Computed Tomography (CT) scanning, c) Stable isotopes δ18O and δ13C, d) micropaleontology (foraminifera, ostracods, diatoms, pollen), e) mineralogical analysis, and f) standard sedimentological techniques (grain size, magnetic susceptibility (MS), Total Organic Carbon (TOC), carbonates content). The chronological framework for the sediment cores was established through 14C radiocarbon dating. The wetlands studied are Aliki salt pond (NE Gulf of Corinth), Klisova lagoon (SW Greece), lake Vouliagmeni (E Gulf of Corinth), Agoulinitsa marsh field (W Peloponnese) and Pappas lagoon (NW Peloponnese). The sites form an E-W transect of southern Greece, an area with high climatic and environmental spatial variability, whereas human occupancy on all areas is recorded from antiquity. Non-destructive, high-resolution techniques used in this thesis have been established as standard in the last decades and have been a great asset in geosciences. Computed Tomography (CT) was conducted in lake Vouliagmeni, Agoulinitsa marsh and Pappas lagoon cores. In contrast, XRF was performed on all core sections except for Pappas lagoon core, where the high assemblage of bivalve shells could lead to bias of Ca. The fundamental parameter behind CT analysis is the Hounsfield units that reflect relative density variations in the sediment. Correlation between HU values and heavy elements like Zr has been detected in all cores, whereas distinct sedimentological facies were recorded according to HU variations. In Agoulinitsa and Pappas lagoon, microstructural characteristics like shells/sediment ratio and root remnants were examined through 3D sections, in which HU boundaries were set accordingly. Lake Vouliagmeni sediment core was characterized by extreme stratigraphic variations with lamination structures alternating with homogenous deposits and event layers. Laminae thickness and boundaries were recorded through 3D rendered volumes with HU boundaries. Micro CT scanning and thin section analysis was also performed to cross-check possible variations. Event sedimentation layers were distinguished through the combined use of CT scanning, XRF and MS, with layers responding to increased HU, MS and Mn values. Statistical assessment of elemental distribution and HU revealed 3 different clusters. Cluster A responded to sedimentation during enhanced evaporation in the area, Cluster B emulated sedimentation during increased chemical weathering in the catchment, and Cluster C reflected the homogenous deposits. Aliki salt pond is located in a highly tectonic region, at the northeast part of the Gulf of Corinth in Greece. Beachrock deposits that form a barrier between the salt pond and the marine environment play an essential role in the evolution of the area. The chronological framework was set at ca. 3100 cal BP by four 14C radiocarbon dates and the established evolutionary model indicate four different changes taking place during this period in the study area. From around 3100 to 1600 cal BP, a transition from a closed to an open lagoonal environment, was identified, interrupted by a terrestrial fluvial deposit at ca. 2500 cal BP. A shift toward a closed lagoonal system at around 1600 cal BP and the establishment of a salt pond environment seem to correlate with tectonic activity. The study provides important information about the evolution of the coastal landscape in such an active tectonic region and points the interaction between regional human activity and climatic changes during the late-Holocene period.Klisova lagoon is located in the eastern part of Messolonghi-Etoliko wetland, the biggest lagoonal complex of Greece and an area of great environmental interest. For the last 4700 cal BP, the freshwater influx, the progradation of the Evinos river delta and related geomorphological changes control the environmental conditions (e.g. depth and salinity) in the lagoon system. Considering the centennial temporal resolution of our analyses, small offsets of c.a. 50 years due to the lack of regional reservoir correction do not impact the reported radiocarbon ages considerably. Prior to 4000 cal BP, a relatively shallow water depth, significant terrestrial/freshwater input and increased weathering in the lagoon area are inferred. Elemental proxies and increased dinoflagellate and foraminifera abundances, which indicate marine conditions with prominent freshwater influxes, point to the gradual deepening of the lagoon recorded at the drilling site up to 2000 cal BP. The marine and freshwater conditions equilibrium sets at 1300 cal BP, and the lagoonal system seems to reach its present state. Maxima of anthropogenic pollen indicators during the Mycenaean (3200 cal BP), Hellenistic (2200 cal BP) and Late Byzantine (800 cal BP) periods suggest intervals of increased anthropogenic activities in the study area. Lake Vouliagmeni is subjected to intense climatically and tectonic forces, causing stratigraphic variations, with laminated sediments frequently interrupted by homogenous and event sedimentation deposits. Lamination couplets consist of aragonite layers alternating with detrital and organic residues and form during periods of seawater intrusion and stratification of the lake water. The discontinuous occurrence of laminated deposits excludes a varve based chronology from being established but still highlights the susceptibility of the lake to record environmental and climatically driven changes. Our synthesis model for regional climatic reconstruction and local environmental changes derives from δ18O and δ13C data from the laminated and homogenous sediments studied separately depending on the dominant carbonate mineral. This is further strengthened by high-resolution geochemical proxies, diatom and sedimentological data. Regional climatic trajectories from key sites and possible links to the lake Vouliagmeni record are explored in response to atmospheric circulation patterns variations. Phases of overall humid conditions are recorded by the increased inflow of siliciclastic material in the lake and negative δ18Obulk values. In contrast, periods of marine intrusion and enhanced evaporation are recorded by aragonite precipitation, increased δ18OAr values and laminations. The driving mechanism behind laminae formation seems to be marine intrusions, leading to pycnocline stabilization and increased evaporation of lake surface waters during summer months. Climatic oscillations recorded during the Holocene, apart from their duration, do not exceed events of the last millennia.


2021 ◽  
Vol 922 (2) ◽  
pp. 256
Author(s):  
Giulia Perotti ◽  
Henning O. Sørensen ◽  
Henning Haack ◽  
Anja C. Andersen ◽  
Dario Ferreira Sanchez ◽  
...  

Abstract Protoplanetary disks are dust- and gas-rich structures surrounding protostars. Depending on the distance from the protostar, this dust is thermally processed to different degrees and accreted to form bodies of varying chemical compositions. The primordial accretion processes occurring in the early protoplanetary disk such as chondrule formation and metal segregation are not well understood. One way to constrain them is to study the morphology and composition of forsteritic grains from the matrix of carbonaceous chondrites. Here, we present high-resolution ptychographic X-ray nanotomography and multimodal chemical microtomography (X-ray diffraction and X-ray fluorescence) to reveal the early history of forsteritic grains extracted from the matrix of the Murchison CM2.5 chondrite. The 3D electron density maps revealed, at unprecedented resolution (64 nm), spherical inclusions containing Fe–Ni, very little silica-rich glass and void caps (i.e., volumes where the electron density is consistent with conditions close to vacuum) trapped in forsterite. The presence of the voids along with the overall composition, petrological textures, and shrinkage calculations is consistent with the grains experiencing one or more heating events with peak temperatures close to the melting point of forsterite (∼2100 K), and subsequently cooled and contracted, in agreement with chondrule-forming conditions.


2020 ◽  
Vol 39 (5) ◽  
pp. 194-201
Author(s):  
Ł. Syrocki ◽  
K. Słabkowska ◽  
E. Węder ◽  
M. Polasik ◽  
J. Rzadkiewicz

AbstractIn order to allow the advanced interpretation of the X-ray spectra registered by the high-resolution crystal KX1 spectrometer on the JET with an ITER-like wall, especially to determine how the relative emission contributions of tungsten and molybdenum ions change during a JET discharge, the X-ray spectra have been carefully modeled over a narrow wavelength range. The simulations have been done in the framework of Collisional–Radiative model implemented in Flexible Atomic Code for an electron density (ne = 2.5 × 1019 m−3), and electron temperatures between Te = 3.0 keV and Te = 4.5 keV, typical for JET. Moreover, performed detailed analysis in the framework of the proposed procedure can be useful in determining temperature of a high temperature plasma generated in tokamaks.


2020 ◽  
Vol 192 ◽  
pp. 108093 ◽  
Author(s):  
Elena Dilonardo ◽  
Michele Nacucchi ◽  
Fabio De Pascalis ◽  
Mauro Zarrelli ◽  
Cinzia Giannini

1983 ◽  
Vol 101 ◽  
pp. 253-260
Author(s):  
W. H.-M. Ku ◽  
K. Long ◽  
R. Pisarski ◽  
M. Vartanian

High quality X-ray spectral and imaging observations of the Cygnus Loop have been obtained with three different instruments. The High Resolution Imager (HRI) on the Einstein Observatory was used to obtain arcsecond resolution images of select bright regions in the Cygnus Loop which permit detailed comparisons between the X-ray, optical, and radio structure of the Loop. The Imaging Proportional Counter (IPC) on the Einstein Observatory was used to obtain an arcminute resolution map of essentially the full Loop structure. Finally, an Imaging Gas Scintillation Proportional Counter (IGSPC), carried aloft by a sounding rocket last fall, obtained modest resolution, spatially resolved spectrophotometry of the Cygnus Loop. An X-ray map of the Loop in the energy of the 0 VIII line was obtained. These data combine to yield a very powerful probe of the abundance, temperature, and density distribution of material in the supernova remnant, and in the interstellar medium.


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