Multivariate Data Analysis for Root Cause Analyses and Time-of-Flight Secondary Ion Mass Spectrometry

Multivariate Data Analysis for Root Cause Analyses and Time-of-Flight Secondary Ion Mass Spectrometry PDF

Author: Danica Heller-Krippendorf

Publisher: Springer Nature

Published: 2019-10-31

Total Pages: 195

ISBN-13: 3658285028

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Danica Heller-Krippendorf develops concepts and approaches optimizing the applicability of MVA on data sets from an industrial context. They enable more time-efficient MVA of the respective ToF‐SIMS data. Priority is given to two main aspects by the author: First, the focus is on strategies for a more time-efficient collection of the input data. This includes the optimal selection of the number of replicate measurements, the selection of input data and guidelines for the selection appropriate data preprocessing methods. Second, strategies for more efficient analysis of MVA results are presented. ​About the Author: Danica Heller-Krippendorf did her research and dissertation at the University of Siegen, Germany, in collaboration with a German analytical service company. Now she is engineer in analytics at a DAX company.

Time-of-flight Secondary Ion Mass Spectrometry

Time-of-flight Secondary Ion Mass Spectrometry PDF

Author: Joanna Lee

Publisher:

Published: 2011

Total Pages:

ISBN-13:

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Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful technique for the analysis of organic surfaces and interfaces for many innovative technologies. However, despite recent developments, there are still many issues and challenges hindering the robust, validated use of ToF-SIMS for quantitative measurement. These include: the lack of metrology and fundamental understanding for the use of novel cluster primary ion beams such as C60n+ and Ar2000 +; the need for validated and robust measurement protocols for difficult samples, such as those with significant micron scale surface topography; the lack of guidance on novel data analysis methods including multivariate analysis which have the potential to simplify many time-consuming and intensive analyses in industry; and the need to establish best practice to improve the accuracy of measurements. This thesis describes research undertaken to address the above challenges. Sample topography and field effects were evaluated experimentally using model conducting and insulating fibres and compared with computer simulations to provide recommendation to diagnose and reduce the effects. Two popular multivariate methods, principal component analysis (PCA) and multivariate curve resolution (MCR), were explored using mixed organic systems consisting of a simple polymer blend and complex hair fibres treated with a multi-component formulation to evaluate different multivariate and data preprocessing methods for the optimal identification, localisation and quantification of the chemical components. Finally, cluster ion beams C60 n+ and ArSOO-2S00 + were evaluated on an inorganic surface and an organic delta layer reference material respectively to elucidate the fundamental metrology of cluster ion sputtering and pave the way for their use in organic depth profiling. These studies provide the essential metrological foundation to address frontier issues in surface and nanoanalysis and extend the measurement capabilities ofToF-SIMS.

Accounting for the Dead Time in Analysis of Time of Flight Secondary Ion Mass Spectrometry Data

Accounting for the Dead Time in Analysis of Time of Flight Secondary Ion Mass Spectrometry Data PDF

Author: Negar Shahrokhesfahani

Publisher:

Published: 2018

Total Pages:

ISBN-13:

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Time of Flight Secondary Ion Mass Spectrometry (ToF SIMS) is a powerful tool for advanced surface analysis. It produces large data sets, which consist of mass spectra at each pixel at an imaged area. Many ToF SIMS instruments use a type of detector that suffers from two problems that lead to non-linearity in the measured sample properties: detector saturation and dead time. Linearity in this type of system is defined as the proportionality of the measured and true ion counts. Non-linearity can influence the interpretation of the data with methods such as multivariate analysis. "Detector saturation" happens when more than one ion arrives at the detector in the time interval related to one specific channel but the detector records only a single count. "Dead time" is when one event happens at a certain channel and the detector become insensitive to subsequent ions arriving within the dead time window. These problems both lead to under-counting of ions. In this thesis, we mainly focus on correcting for the dead time effects. Using extensive simulations, we first characterize the adverse effects of dead time on the output and evaluate quality of existing ways to "correct" for dead time effects. Then, we propose a novel method using the Maximum Likelihood Estimation (MLE) to estimate the true spectrum for the measured data. Specifically, we incorporate the statistical distribution of the dead time affected data in MLE, which leads to a new method for dead time correction.

Visualizing Chemistry

Visualizing Chemistry PDF

Author: National Research Council

Publisher: National Academies Press

Published: 2006-06-01

Total Pages: 222

ISBN-13: 030916463X

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Scientists and engineers have long relied on the power of imaging techniques to help see objects invisible to the naked eye, and thus, to advance scientific knowledge. These experts are constantly pushing the limits of technology in pursuit of chemical imagingâ€"the ability to visualize molecular structures and chemical composition in time and space as actual events unfoldâ€"from the smallest dimension of a biological system to the widest expanse of a distant galaxy. Chemical imaging has a variety of applications for almost every facet of our daily lives, ranging from medical diagnosis and treatment to the study and design of material properties in new products. In addition to highlighting advances in chemical imaging that could have the greatest impact on critical problems in science and technology, Visualizing Chemistry reviews the current state of chemical imaging technology, identifies promising future developments and their applications, and suggests a research and educational agenda to enable breakthrough improvements.

Secondary Data Analysis

Secondary Data Analysis PDF

Author: Thomas P. Vartanian

Publisher: Oxford University Press

Published: 2011

Total Pages: 225

ISBN-13: 019538881X

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This slim volume is one of a number of excellent guides published as part of Oxford's "Pocket Guide to Social Work Research Methods" series. Compact but comprehensive, it provides a thorough introduction to one of the fastest-growing genres of research in the social work field today: secondary data analysis. After an all-too-brief summary of what constitutes this genre and a balanced analysis of its advantages and disadvantages, Vartanian (Bryn Mawr) provides guidelines for those considering the feasibility and appropriateness of using secondary data in their work. He then offers extensive summaries of 29 of the most commonly used secondary data sets. For all of the data sets, he provides a full and complete description, including key characteristics and where and how to access them. He also provides, most valuably, citations to examples of how researchers have recently used them in their empirical work. Rather redundantly, a similar package of information appears in appendixes at the end of the book. This is an admirable contribution whose only detractions are the rather random and poorly identified screenshots and other "pictures" interspersed throughout the text. Those seriously considering using secondary data analysis in their research should find this book immensely beneficial. Summing Up: Highly recommended. Graduate students and faculty/researchers. Graduate Students; Researchers/Faculty. Reviewed by J. C. Altman.

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