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Articles 1 - 11 of 11
Full-Text Articles in Physical Sciences and Mathematics
Use And Misuse Of X-Ray Photoelectron Spectroscopy (Xps): Reproducibility, Gross Errors, Data Reporting, And Peak Fitting, George Hobbs Major
Use And Misuse Of X-Ray Photoelectron Spectroscopy (Xps): Reproducibility, Gross Errors, Data Reporting, And Peak Fitting, George Hobbs Major
Theses and Dissertations
X-ray photoelectron spectroscopy (XPS) is the most widely used surface analysis technique for chemically probing surfaces. Its popularity stems from the large amount of information that can be gathered about the electronic states of the atoms it probes, including core shell information and valence electron information. Simple qualitative analysis (peak identification) can often be performed, but quantitative analysis is a much more complicated process. Although XPS usage has increased dramatically, so has the amount of erroneous analysis observed in the literature. In my thesis, I first present a perspective on how to improve the quality of surface and material data …
Atomic Layer Deposition And High Sensitivity-Low Energy Ion Scattering For The Determination Of The Surface Silanol Density On Glass And Unsupervised Exploratory Data Analysis With Summary Statistics And Other Methods, Tahereh Gholian Avval
Theses and Dissertations
With the increasing importance of hand-held devices with touch displays, the need for flat panel displays (FPDs) will likely increase in the future. Glass is the most important substrate for FPD manufacturing, where both its bulk and surface properties are critical for its performance. Many properties of the glass used in FPDs are controlled by its surface chemistry. Surface hydroxyls are the most important functional groups on a glass surface, which control processes that occurs on oxide surfaces, including wetting, adhesion, electrostatic charging and discharge, and the rate of contamination. In this dissertation, I present a new approach for determining …
Fabrication Of Advanced Materials For Chromatography, Sample Preparation, And Separations, And Accompanying Material Characterization, Dhananjay I. Patel
Fabrication Of Advanced Materials For Chromatography, Sample Preparation, And Separations, And Accompanying Material Characterization, Dhananjay I. Patel
Theses and Dissertations
My dissertation primarily focuses on the fabrication of materials for solid phase microextraction (SPME) and separation devices. In my first project, I used direct current magnetron sputtering (DCMS) to prepare sputtered silicon coatings on fused silica fibers. These fibers were then subjected to the chemical vapor deposition of 6-phenyhexylsilane (6-PH) as a stationary phase. Six different types of fibers were made using two different throw distances (4 cm and 20 cm) and three different silicon thicknesses (0.5, 1.8, and 2.8 µm). These coatings were characterized by time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), …
Thin Film Deposition On Powder Substrates Using Ald And Its Characterization Using Xps, Tem, And Se, Dhruv Shah
Thin Film Deposition On Powder Substrates Using Ald And Its Characterization Using Xps, Tem, And Se, Dhruv Shah
Theses and Dissertations
The major part of my dissertation consists of thin films deposited using atomic layer deposition on flat and powder substrates. It details the various optimization experiments for process parameters like dose time, purge time, temperature, and pressure on silicon shards and powder substrates. Spectroscopic ellipsometry (SE) was used to characterize these films over a wide wavelength range (191-1688 nm). An optical model with a BEMA (Bruggeman effective medium approximation) layer was used to fit the ellipsometric data to investigate the optical properties of the alumina surface. The optimized process parameters on the flat surfaces were used for coating powder substrates. …
Exploration Of Sputtered Thin Films—E.G., In Sample Preparation And Material Characterization, Tuhin Roychowdhury
Exploration Of Sputtered Thin Films—E.G., In Sample Preparation And Material Characterization, Tuhin Roychowdhury
Theses and Dissertations
My dissertation focuses on (i) the development sputtered films for solid phase microextraction (SPME) and (ii) the comprehensive characterization of materials using a suite of analytical techniques. Chapter 1 reviews the basics of SPME. This chapter also contains (i) a discussion of various sputtering techniques, (ii) a discussion of two techniques I focused on most of my work: spectroscopic ellipsometry (SE) and X-ray photoelectron spectroscopy (XPS). Chapter 2 focuses the major part of my work, which is to prepare new solid phases/adsorbents for SPME via silicon sputtering followed by thermal deposition of a polymer, polydimethylsiloxane (PDMS). PDMS was deposited by …
Preparation And Detailed X-Ray Photoelectron Spectroscopy And Spectroscopic Ellipsometryanalysis Of Ultrathin Protective Coatings, Brian Ivins Johnson
Preparation And Detailed X-Ray Photoelectron Spectroscopy And Spectroscopic Ellipsometryanalysis Of Ultrathin Protective Coatings, Brian Ivins Johnson
Theses and Dissertations
Ultra-thin films (UTFs) are important in many applications, seen in the semiconductor industry, in chromatography, in sensing, in microfluidics, in aerospace, and in robotics. They also protect materials from corrosion, change surface energies, limit water intrusion into materials, allow material self-cleaning and self-healing, provide scratch resistance, and impart other specific chemical properties. In many cases, UTFs drastically alter surface properties and therefore their applications. It is imperative that proper and consistent characterization be performed on coatings to confirm and understand their desired properties. In Chapter two, Al oxidation under MgF2 protective layers is studied using real time X-ray photoelectron spectroscopy …
Preparation, Functionalization, And/Or Characterization By X-Ray Photoelectron Spectroscopy Of Carbon Surfaces For Biosensors And Other Materials, Varun Jain
Theses and Dissertations
My dissertation is primarily divided into two parts. The first deals with the preparation, functionalization, and characterization of carbon surfaces prepared by direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HiPIMS) as substrates for bioarrays. Part two discusses applications of XPS peak fitting in surface chemical analysis. Chapter 1, the introduction, includes (i) a discussion of the construction of bioarrays and the preparation of sputtered surfaces, e.g., by DCMS and HiPIMS, and also functionalization (bioconjugate) chemistry with special emphasis on the importance of covalent functionalization of surfaces, and (ii) a discussion of the surface characterization techniques and …
Multi-Instrument Surface Characterization Of Display Glass, Cody Vic Cushman
Multi-Instrument Surface Characterization Of Display Glass, Cody Vic Cushman
Theses and Dissertations
Flat panel displays (FPDs) are microfabricated devices that are often fabricated on specialized glass substrates known as display glass. The surface chemistry of the outer few nanometers of display glass can have an important influence on FPD performance and yield. Dsiplay glass surface characterization is difficult because (i) display glass surface composition varies significantly from its bulk composition; (ii) high-surface area forms of glass, such as fibers and powders, may not have the same surface composition as melt-formed planar surfaces, and (iii) the surface composition of display glass may be altered through exposure to chemical treatments commonly used during flat …
Applications Of Pattern Recognition Entropy (Pre) And Informatics To Data Analysis, Shiladitya Chatterjee
Applications Of Pattern Recognition Entropy (Pre) And Informatics To Data Analysis, Shiladitya Chatterjee
Theses and Dissertations
The primary focus of my work is the application of informatics methods to the fields of materials science and analytical chemistry. The statistical analysis of data has become increasingly important in understanding the properties of materials and analytes. Statistical methods like principal component analysis (PCA) and multivariate curve resolution (MCR) are widely used for analysis in chemistry and other fields given their ability to categorize spectra in an unsupervised way. PCA is relatively easy to apply and has appealing mathematical properties. However, the results can be challenging to interpret, even for experienced users. In contrast, MCR results can be more …
Advanced Data Analysis Tools And Multi-Instrument Material Characterization, Bhupinder Singh
Advanced Data Analysis Tools And Multi-Instrument Material Characterization, Bhupinder Singh
Theses and Dissertations
My dissertation focuses on (i) the development of new analysis tools and methodologies for analyzing X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) data, and (ii) the comprehensive characterization of materials (nanodiamonds) using a multi-instrument approach. Chapter 1 contains (i) a discussion of the two techniques I focused on most in my work: XPS and ToF-SIMS, (ii) a discussion of the common chemometrics techniques used to analyze data from these methods, and (iii) the advantages/rationale behind the multi-instrument characterization of materials. Chapter 2 describes various good practices for obtaining reasonable peak fits in XPS, which can also …
Deposition And Characterization Of Hydrophobic Coatings, Vipul Gupta
Deposition And Characterization Of Hydrophobic Coatings, Vipul Gupta
Theses and Dissertations
Hydrophobic coatings find application in various sectors of the economy including to electronics, textiles, optical devices, and in scientific and commercial equipment. These different applications demand that different hydrophobic coatings posses a range of properties that may include smoothness or roughness, thicknesses on the order of a monolayer or a micron, robustness or the ability to dissolve quickly, transparency or opacity, water resistance or water permeability, electrical conductivity, oleophobicity, etc. However, whatever the final/desired properties, deposition via dry-deposition processes offers significant advantages, including greater reproducibility, increased environmental friendliness, and cost effectiveness on an industrial scale. Herein I explore the chemical …