scholarly journals Single-Ion Deconvolution of Mass Peak Overlaps for Atom Probe Microscopy

2017 ◽  
Vol 23 (2) ◽  
pp. 300-306 ◽  
Author(s):  
Andrew J. London ◽  
Daniel Haley ◽  
Michael P. Moody
Keyword(s):  
Kinetic Energy ◽  
Point Cloud ◽  
Atom Probe ◽  
Resolving Power ◽  
Isotopic Abundance ◽  
Mass Peak ◽  
Peak Overlap ◽  
Mass Resolving Power ◽  
Charge Spectrum ◽  
Isotopic Abundances

AbstractDue to the intrinsic evaporation properties of the material studied, insufficient mass-resolving power and lack of knowledge of the kinetic energy of incident ions, peaks in the atom probe mass-to-charge spectrum can overlap and result in incorrect composition measurements. Contributions to these peak overlaps can be deconvoluted globally, by simply examining adjacent peaks combined with knowledge of natural isotopic abundances. However, this strategy does not account for the fact that the relative contributions to this convoluted signal can often vary significantly in different regions of the analysis volume; e.g., across interfaces and within clusters. Some progress has been made with spatially localized deconvolution in cases where the discrete microstructural regions can be easily identified within the reconstruction, but this means no further point cloud analyses are possible. Hence, we present an ion-by-ion methodology where the identity of each ion, normally obscured by peak overlap, is resolved by examining the isotopic abundance of their immediate surroundings. The resulting peak-deconvoluted data are a point cloud and can be analyzed with any existing tools. We present two detailed case studies and discussion of the limitations of this new technique.

On the Field Evaporation Behavior of a Model Ni-Al-Cr Superalloy Studied by Picosecond Pulsed-Laser Atom-Probe Tomography

2008 ◽  
Vol 14 (6) ◽  
pp. 571-580 ◽  
Author(s):  
Yang Zhou ◽  
Christopher Booth-Morrison ◽  
David N. Seidman
Keyword(s):  
Atom Probe Tomography ◽  
Mass Spectra ◽  
Pulsed Laser ◽  
Picosecond Laser ◽  
Atom Probe ◽  
Resolving Power ◽  
Noise Levels ◽  
Thermally Activated ◽  
Mass Resolving Power

AbstractThe effects of varying the pulse energy of a picosecond laser used in the pulsed-laser atom-probe (PLAP) tomography of an as-quenched Ni-6.5 Al-9.5 Cr at.% alloy are assessed based on the quality of the mass spectra and the compositional accuracy of the technique. Compared to pulsed-voltage atom-probe tomography, PLAP tomography improves mass resolving power, decreases noise levels, and improves compositional accuracy. Experimental evidence suggests that Ni2+, Al2+, and Cr2+ ions are formed primarily by a thermally activated evaporation process, and not by post-ionization of the ions in the 1+ charge state. An analysis of the detected noise levels reveals that for properly chosen instrument parameters, there is no significant steady-state heating of the Ni-6.5 Al-9.5 Cr at.% tips during PLAP tomography.

Understanding of Capping Effects on the Tip Shape Evolution and on the Atom Probe Data of Bulk LaAlO3 Using Transmission Electron Microscopy

2017 ◽  
Vol 23 (2) ◽  
pp. 329-335 ◽  
Author(s):  
Chang-Min Kwak ◽  
Young-Tae Kim ◽  
Chan-Gyung Park ◽  
Jae-Bok Seol
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe ◽  
Resolving Power ◽  
Shape Evolution ◽  
Oxide Materials ◽  
Field Evaporation ◽  
Laser Illumination ◽  
Transmission Electron ◽  
Mass Resolving Power

AbstractTwo challenges exist in laser-assisted atom probe tomography (APT). First, a drastic decline in mass-resolving power is caused, not only by laser-induced thermal effects on the APT tips of bulk oxide materials, but also the associated asymmetric evaporation behavior; second, the field evaporation mechanisms of bulk oxide tips under laser illumination are still unclear due to the complex relations between laser pulse and oxide materials. In this study, both phenomena were investigated by depositing Ni- and Co-capping layers onto the bulk LaAlO3 tips, and using stepwise APT analysis with transmission electron microscopy (TEM) observation of the tip shapes. By employing the metallic capping, the heating at the surface of the oxide tips during APT analysis became more symmetrical, thereby enabling a high mass-resolving power in the mass spectrum. In addition, the stepwise microscopy technique visualized tip shape evolution during APT analysis, thereby accounting for evaporation sequences at the tip surface. The combination of “capping” and “stepwise APT with TEM,” is applicable to any nonconductors; it provides a direct observation of tip shape evolution, allows determination of the field evaporation strength of oxides, and facilitates understanding of the effects of ultrafast laser illumination on an oxide tip.

scholarly journals Improved Mass Resolving Power and Yield in Atom Probe Tomography

2013 ◽  
Vol 19 (S2) ◽  
pp. 994-995 ◽  
Author(s):  
D.J. Larson ◽  
T.J. Prosa ◽  
J.H. Bunton ◽  
D.P. Olson ◽  
D.F. Lawrence ◽  
...  
Keyword(s):  
Atom Probe Tomography ◽  
Atom Probe ◽  
Resolving Power ◽  
Mass Resolving Power

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

scholarly journals MeasuringContributions to Mass Resolving Power in Atom Probe Tomography

2011 ◽  
Vol 17 (S2) ◽  
pp. 754-755 ◽  
Author(s):  
E Oltman ◽  
T Kelly ◽  
T Prosa ◽  
D Lawrence ◽  
D Larson
Keyword(s):  
Atom Probe Tomography ◽  
Atom Probe ◽  
Resolving Power ◽  
Mass Resolving Power

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

The Influence of Experimental Parameters and Specimen Geometry on the Mass Spectra of Copper During Pulsed-Laser Atom-Probe Tomography

2014 ◽  
Vol 20 (6) ◽  
pp. 1715-1726 ◽  
Author(s):  
R. Prakash Kolli ◽  
Frederick Meisenkothen
Keyword(s):  
Pulse Energy ◽  
Mass Spectra ◽  
Pulsed Laser ◽  
Atom Probe ◽  
Pulse Frequency ◽  
Resolving Power ◽  
Base Temperature ◽  
Mass Resolving Power ◽  
Half Angle ◽  
Tip Radius

AbstractWe have studied the influence of experimental factors and specimen geometry on the quality of the mass spectra in copper (Cu) during pulsed-laser atom-probe tomography. We have evaluated the effects of laser pulse energy, laser pulse frequency, specimen base temperature, specimen tip radius, and specimen tip shank half-angle on the effects of mass resolving power, (m/Δm), at full-width at half-maximum and at full-width at tenth-maximum, the tail size after the major mass-to-charge state (m/n) ratio peaks, and the mass spectra. Our results indicate that mass resolving power improves with decreasing pulse energy between 40 and 80 pJ and decreasing base temperature between 20 and 80 K. The mass resolving power also improves with increasing tip radius and shank half-angle. A pulse frequency of 250 kHz slightly improves the mass resolving power relative to 100 or 500 kHz. The tail size decreases with increasing pulse energy. The mass resolving power improves when the cooling time is reduced, which is influenced by the thermal diffusivity of Cu and the specimen base temperature.

Local Electrode Atom Probes

1998 ◽  
Vol 4 (S2) ◽  
pp. 84-85
Author(s):  
Thomas F. Kelly ◽  
Patrick P. Camus
Keyword(s):  
Thin Film ◽  
Data Collection ◽  
Atom Probe ◽  
Atomic Scale ◽  
Specimen Geometry ◽  
Resolving Power ◽  
Charge Ratio ◽  
Atom Probes ◽  
Mass Resolving Power ◽  
Analytical Standards

The Need for Improvements. Though atom probe techniques have impressive atomic-scale analytical capabilities, there are some definite needs for improvement. The needle shape of APFIM specimens is a difficult geometry to make for many types of materials, especially technologically important thin-film materials. Even though 3DAPs collect more data than traditional APs, the analysis volumes are still small by analytical standards: typically there are fewer than 1 million atoms in an image which is about 15nm x 15nm x 50nm. The data collection rate (up to tens of atoms per second) limits the practical size of analyzed volumes to about 1 million atoms. Poor mass resolution makes it difficult to separate ions of similar mass-to-charge ratio in spectra of approximately 20% of samples. Thus, there are three principal areas where improvements are desirable: 1) specimen geometry, 2) data collection rates, and 3) mass resolving power.

Thin film underlayer effects on mass resolving power in laser-assisted atom probe tomography

2014 ◽  
Vol 551 ◽  
pp. 32-36 ◽  
Author(s):  
K. Tippey ◽  
J.G. Brons ◽  
M. Kapoor ◽  
B. Fu ◽  
G.B. Thompson
Keyword(s):  
Thin Film ◽  
Atom Probe Tomography ◽  
Atom Probe ◽  
Resolving Power ◽  
Mass Resolving Power

scholarly journals Development of an Energy-Sensitive Detector for the Atom Probe Tomography

2021 ◽  
pp. 1-16
Author(s):  
Christian Bacchi ◽  
Gérald Da Costa ◽  
Emmanuel Cadel ◽  
Fabien Cuvilly ◽  
Jonathan Houard ◽  
...  
Keyword(s):  
Atom Probe Tomography ◽  
Atom Probe ◽  
Sensitive Detector ◽  
Mass Peak ◽  
Peak Overlap ◽  
Thin Carbon ◽  
New Type ◽  
Carbon Foils ◽  
New Generation ◽  
The Impact

A position and energy-sensitive detector has been developed for atom probe tomography (APT) instruments in order to deal with some mass peak overlap issues encountered in APT experiments. Through this new type of detector, quantitative and qualitative improvements could be considered for critical materials with mass peak overlaps, such as nitrogen and silicon in TiSiN systems, or titanium and carbon in cemented carbide materials. This new detector is based on a thin carbon foil positioned on the front panel of a conventional MCP-DLD detector. According to several studies, it has been demonstrated that the impact of ions on thin carbon foils has the effect of generating a number of transmitted and reflected secondary electrons. The number generated mainly depends on both the kinetic energy and the mass of incident particles. Despite the fact that this phenomenon is well known and has been widely discussed for decades, no studies have been performed to date for using it as a means to discriminate particles energy. Therefore, this study introduces the first experiments on a potential new generation of APT detectors that would be able to resolve mass peak overlaps through the energy-sensitivity of thin carbon foils.

Calculation of the Ion Optical Properties of Inhomogeneous Magnetic Sector Fields Part 3: Oblique Incidence and Exit at Curved Boundaries

1959 ◽  
Vol 14 (9) ◽  
pp. 822-827 ◽  
Author(s):  
H. A. Tasman ◽  
A. J. H. Boerboom ◽  
H. Wachsmuth
Keyword(s):  
Oblique Incidence ◽  
Normal Incidence ◽  
Second Order ◽  
Resolving Power ◽  
High Mass ◽  
Curved Boundaries ◽  
Magnetic Sector ◽  
Mass Resolving Power ◽  
Mass Dispersion ◽  
Fringing Fields

In previous papers 1.2we presented the radial second order imaging properties of inhomogeneous magnetic sector fields with normal incidence and exit at plane boundaries. These fields may provide very high mass resolving power and mass dispersion without increase in radius or decrease of slit widths. In the present paper the calculations are extended to include the effect of oblique incidence and exit at curved boundaries. The influence of the fringing fields on axial focusing when the boundaries are oblique, is accounted for. It is shown that the second order angular aberration may Le eliminated by appropriate curvature of the boundaries.

Numerical analysis of trajectories in a Cassinian ion trap of second order with trap door ion inlet

2021 ◽  
Vol 27 (1) ◽  
pp. 3-12
Author(s):  
Bjoern Raupers ◽  
Hana Medhat ◽  
Juergen Grotemeyer ◽  
Frank Gunzer
Keyword(s):  
Ion Trap ◽  
Ion Traps ◽  
Second Order ◽  
Resolving Power ◽  
Periodic Pattern ◽  
Ion Motion ◽  
Trap Door ◽  
Mass Resolving Power ◽  
Long Time ◽  
The Fourier Transform

Ion traps like the Orbitrap are well known mass analyzers with very high resolving power. This resolving power is achieved with help of ions orbiting around an inner electrode for long time, in general up to a few seconds, since the mass signal is obtained by calculating the Fourier Transform of the induced signal caused by the ion motion. A similar principle is applied in the Cassinian Ion Trap of second order, where the ions move in a periodic pattern in-between two inner electrodes. The Cassinian ion trap has the potential to offer mass resolving power comparable to the Orbitrap with advantages regarding the experimental implementation. In this paper we have investigated the details of the ion motion analyzing experimental data and the results of different numerical methods, with focus on increasing the resolving power by increasing the oscillation frequency for ions in a high field ion trap. In this context the influence of the trap door, a tunnel through which the ions are injected into the trap, on the ion velocity becomes especially important.

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