scholarly journals Measuring fluorine in uranium oxyfluoride particles using secondary ion mass spectrometry for nuclear forensics

2011 ◽  
Vol 1 (1) ◽  
pp. 7-11 ◽  
Author(s):  
Ruth Kips ◽  
M. J. Kristo ◽  
I. D. Hutcheon ◽  
Z. Wang ◽  
T. J. Johnson ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Secondary Ion Mass Spectrometry ◽  
Uranium Hexafluoride ◽  
High Humidity ◽  
Enrichment Facility ◽  
Single Particles ◽  
Energy Agency ◽  
Dry Air ◽  
Lighting Conditions ◽  
Secondary Ion

Abstract Gaseous uranium hexafluoride (UF6) is used for the enrichment of uranium and is known to be a very reactive and volatile gas. When a small amount of UF6 is released in the environment, it forms uranium oxyfluoride (UO2F2) particles and hydrogen fluoride from the reaction with atmospheric moisture. The UO2F2 particles settle on various surfaces within the enrichment facility where they are collected by safeguards organizations such as the International Atomic Energy Agency (IAEA) through a technique called environmental sampling. Despite their small size, the uranium isotopic composition of these particles is used to determine whether an enrichment facility is compliant with its declarations. Additional and complementary information on the particles' source, formation process and exposure history can be obtained from elemental, molecular and morphological analysis. As fluorine is not always detected in uranium particles originating from enrichment facilities, it is assumed that UO2F2 is unstable under certain environmental conditions. This study aims to determine how those environmental conditions affect the relative amount of fluorine in UO2F2 particles. Expressly for the purpose of this work, we prepared a set of UO2F2 particle samples from the hydrolysis of UF6 and stored these samples in environmental chambers at different temperature, humidity and lighting conditions. The NanoSIMS secondary ion mass spectrometer, with a nanometer-scale spatial resolution, was used to measure the F+/U+ secondary ion ratio of individual particles immediately after sample preparation, and at different time intervals. NanoSIMS analyses on single particles stored up to 7 months in dry air did not detect a significant decrease in the relative amount of fluorine. The exposure to high humidity however, resulted in a much lower F+/U+ ratio, up to 2 orders of magnitude below that of the particles stored in dry air. It should be noted that fluorine was still detected in these samples, even after 7 months of high humidity exposure.

Molecular Surface Imaging of Particles Using Microprobe Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

1996 ◽  
Vol 54 ◽  
pp. 1046-1047
Author(s):  
R.W. Linton ◽  
T.F. Fister ◽  
S.S. Summers ◽  
G.S. Strossman ◽  
M.J. Holland ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Time Of Flight ◽  
Surface Damage ◽  
Molecular Surface ◽  
Photochemical Degradation ◽  
Single Particles ◽  
Tof Sims ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

The objective of this research is to develop imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS) to characterize ultra-thin organic films on microscopic particles. An initial application is to evaluate the surface chemistry of polycyclic organic matter (POM) on combustion-generated particles as an area of fundamental interest in the assessment of the environmental fate and impact of carcinogenic pollutants.Controlled deposition of POM monolayers was achieved using either gas or solution phase coating on model particles such as silica, as well as on authentic environmental particles such as coal flyash or soot. Another aspect of the work was to monitor surface transformations of adsorbed POM involving photochemical degradation or reactions with gaseous pollutants such as nitrogen oxides. For the first time, variations in POM adsorption and reactivity have been probed as a function of particle type by the use of time-of-flight secondary ion mass spectrometry (TOF-SIMS) to perform surface analysis on single particles. Results using a pulsed gallium microbeam source on a TOF-SIMS indicated that 0.1 monolayer coverages of individual POM species can be detected as quasimolecular ions from single particles with diameters typically in the 5 μm range. Primary ion doses were <1013 ions/cm2 to minimize surface damage during a typical 10 min spectrum acquisition from an 40x40 ftm image field. Correlation of in situ measurements using TOF-SIMS with traditional solvent extraction and chromatographic results, including LC or GC-MS, allowed for more detailed assessments of the sensitivity and quantitative capabilities of TOF-SIMS. The combination of monolayer analysis with microanalysis creates severe challenges to sensitivity since the total number of molecules within the analytical volume is so small (< 107 POM molecules on a lμm2 particle area)

Understanding Glass Deterioration in Museum Collections through Raman Spectroscopy and SIMS analysis

2004 ◽  
Vol 852 ◽  
Author(s):  
Laurianne Robinet ◽  
Katherine Eremin ◽  
Sarah Fearn ◽  
Colin Pulham ◽  
Christopher Hall
Keyword(s):  
Raman Spectroscopy ◽  
Secondary Ion Mass Spectrometry ◽  
Glass Structure ◽  
High Humidity ◽  
Museum Collections ◽  
Humid Atmosphere ◽  
Polluted Atmosphere ◽  
Sims Analysis ◽  
Secondary Ion ◽  
Acetic Acids

ABSTRACTThe combination of Raman spectroscopy and Secondary Ion Mass Spectrometry can improve understanding of the chemistry of the glass alteration process. Formic and acetic acids play an important role in the alteration of museum glass objects placed in a humid atmosphere. Raman spectroscopy indicates that the soda-rich glass structure is modified differently when exposed to a humid versus a humid and polluted atmosphere at 60°C. Formic acid was not formed from soda-rich glass in the presence of carbon dioxide, high humidity and light.

Application of secondary ion mass spectrometry to the identification of single particles of uranium and their isotopic measurement

1998 ◽  
Vol 53 (9) ◽  
pp. 1289-1302 ◽  
Author(s):  
Gabriele Tamborini ◽  
Maria Betti ◽  
Vittorio Forcina ◽  
Tania Hiernaut ◽  
Bruno Giovannone ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Single Particles ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

Aspects of high-resolution imaging with a scanning ion microprobe

1986 ◽  
Vol 44 ◽  
pp. 750-751
Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
Y. L. Wang
Keyword(s):  
Metal Ion ◽  
Secondary Ion Mass Spectrometry ◽  
Chromatic Aberration ◽  
Ion Source ◽  
Ion Microprobe ◽  
Emission Pattern ◽  
Intrinsic Resolution ◽  
Resolution Imaging ◽  
20 Nm ◽  
Secondary Ion

We have shown the feasibility of 20 nm lateral resolution in both topographic and elemental imaging using probes of this size from a liquid metal ion source (LMIS) scanning ion microprobe (SIM). This performance, which approaches the intrinsic resolution limits of secondary ion mass spectrometry (SIMS), was attained by limiting the size of the beam defining aperture (5μm) to subtend a semiangle at the source of 0.16 mr. The ensuing probe current, in our chromatic-aberration limited optical system, was 1.6 pA with Ga+ or In+ sources. Although unique applications of such low current probes have been demonstrated,) the stringent alignment requirements which they imposed made their routine use impractical. For instance, the occasional tendency of the LMIS to shift its emission pattern caused severe misalignment problems.

How SIMS microscopy can be used in medicine

1992 ◽  
Vol 50 (2) ◽  
pp. 1602-1603
Author(s):  
Philippe Fragu
Keyword(s):  
Mass Spectrometry ◽  
Biomedical Applications ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Elements ◽  
Biological Applications ◽  
The Past ◽  
Potential Source ◽  
Secondary Ion ◽  
Chemical Integrity ◽  
Scientific Endeavour

The identification, localization and quantification of intracellular chemical elements is an area of scientific endeavour which has not ceased to develop over the past 30 years. Secondary Ion Mass Spectrometry (SIMS) microscopy is widely used for elemental localization problems in geochemistry, metallurgy and electronics. Although the first commercial instruments were available in 1968, biological applications have been gradual as investigators have systematically examined the potential source of artefacts inherent in the method and sought to develop strategies for the analysis of soft biological material with a lateral resolution equivalent to that of the light microscope. In 1992, the prospects offered by this technique are even more encouraging as prototypes of new ion probes appear capable of achieving the ultimate goal, namely the quantitative analysis of micron and submicron regions. The purpose of this review is to underline the requirements for biomedical applications of SIMS microscopy.Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue.

Advances in imaging SIMS studies of stained and BrdU-labelled human metaphase chromosomes

1995 ◽  
Vol 53 ◽  
pp. 932-933
Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
R. Espinosa ◽  
M. M. Le Beau
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Analytical Sensitivity ◽  
Metaphase Chromosomes ◽  
Banding Patterns ◽  
Sector Mass Spectrometer ◽  
Staining Methods ◽  
The University ◽  
Secondary Ion ◽  
Better Than

We have shown previously that isotope-labelled nucleotides in human metaphase chromosomes can be detected and mapped by imaging secondary ion mass spectrometry (SIMS), using the University of Chicago high resolution scanning ion microprobe (UC SIM). These early studies, conducted with BrdU- and 14C-thymidine-labelled chromosomes via detection of the Br and 28CN- (14C14N-> labelcarrying signals, provided some evidence for the condensation of the label into banding patterns along the chromatids (SIMS bands) reminiscent of the well known Q- and G-bands obtained by conventional staining methods for optical microscopy. The potential of this technique has been greatly enhanced by the recent upgrade of the UC SIM, now coupled to a high performance magnetic sector mass spectrometer in lieu of the previous RF quadrupole mass filter. The high transmission of the new spectrometer improves the SIMS analytical sensitivity of the microprobe better than a hundredfold, overcoming most of the previous imaging limitations resulting from low count statistics.

Imaging of Al-Li-Cu alloys with a Scanning Ion Microprobe

1990 ◽  
Vol 48 (2) ◽  
pp. 314-315
Author(s):  
K.K. Soni ◽  
D.B. Williams ◽  
J.M. Chabala ◽  
R. Levi-Setti ◽  
D.E. Newbury
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Equilibrium Phase ◽  
Icosahedral Symmetry ◽  
Ion Microprobe ◽  
X Ray ◽  
Cu Alloys ◽  
Two Phases ◽  
The University ◽  
Secondary Ion

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.

Applications of Time-OF-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

1990 ◽  
Vol 48 (2) ◽  
pp. 308-309
Author(s):  
Bruno Schueler ◽  
Robert W. Odom
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Structural Information ◽  
Time Of Flight ◽  
Biological Tissues ◽  
Polymer Surfaces ◽  
Tof Sims ◽  
Secondary Ions ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.

Near-Surface Aggregation of Sn In Heavily Sn-Doped GaAs Films Grown By Molecular Beam Epitaxy

1985 ◽  
Vol 43 ◽  
pp. 368-369
Author(s):  
S. H. Chen
Keyword(s):  
Molecular Beam Epitaxy ◽  
Cross Section ◽  
Electron Spectroscopy ◽  
Molecular Beam ◽  
Surface Segregation ◽  
Secondary Ion Mass Spectrometry ◽  
Specimen Preparation ◽  
Near Surface ◽  
Gaas Films ◽  
Secondary Ion

Sn has been used extensively as an n-type dopant in GaAs grown by molecular-beam epitaxy (MBE). The surface accumulation of Sn during the growth of Sn-doped GaAs has been observed by several investigators. It is still not clear whether the accumulation of Sn is a kinetically hindered process, as proposed first by Wood and Joyce, or surface segregation due to thermodynamic factors. The proposed donor-incorporation mechanisms were based on experimental results from such techniques as secondary ion mass spectrometry, Auger electron spectroscopy, and C-V measurements. In the present study, electron microscopy was used in combination with cross-section specimen preparation. The information on the morphology and microstructure of the surface accumulation can be obtained in a fine scale and may confirm several suggestions from indirect experimental evidence in the previous studies.

Trace nanoanalysis

1994 ◽  
Vol 52 ◽  
pp. 940-941
Author(s):  
D. E. Newbury ◽  
R. D. Leapman
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Detection Efficiency ◽  
Volume Element ◽  
And Performance ◽  
Trace Constituents ◽  
Secondary Ion ◽  
Concentration Levels ◽  
Structure Properties

Trace constituents, which can be very loosely defined as those present at concentration levels below 1 percent, often exert influence on structure, properties, and performance far greater than what might be estimated from their proportion alone. Defining the role of trace constituents in the microstructure, or indeed even determining their location, makes great demands on the available array of microanalytical tools. These demands become increasingly more challenging as the dimensions of the volume element to be probed become smaller. For example, a cubic volume element of silicon with an edge dimension of 1 micrometer contains approximately 5×1010 atoms. High performance secondary ion mass spectrometry (SIMS) can be used to measure trace constituents to levels of hundreds of parts per billion from such a volume element (e. g., detection of at least 100 atoms to give 10% reproducibility with an overall detection efficiency of 1%, considering ionization, transmission, and counting).

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