Process spectroscopy,—characterization density

In another smdy, samples of depleted uranium oxide manufactured through different processes were characterized (Hastings et al. 2008). Three types of uranium oxides were prepared from uranyl nitrate hexahydrate (U02(N03)2-6H20) at different temperatures UO2 at 500°C-700°C, UjOg at 800°C-1100°C, and UO3 at 350°C-450°C. Optical spectroscopy and particle fractionation were used to characterize the oxides. The color of the oxides, their density, and granular appearance (aerodynamic diameter and size distribution) were somewhat affected by the preparation conditions. The gamma spectrum of the samples was also recorded. The conclusion was that variations in the processing conditions of the uranium oxides were reflected in the density and particle size distribution and these characteristics could be used for nuclear forensics. 

The film electrodeposition process was studied by means of linear sweep voltammetry. The rate of electrochemical reaction was determined from current density (current-potential curves). The film deposits were characterized by chemical analysis, IR - spectroscopy, XRD, TG, TGA and SEM methods. 

A very common and useful approach to studying the plasma polymerization process is the careful characterization of the polymer films produced. A specific property of the films is then measured as a function of one or more of the plasma parameters and mechanistic explanations are then derived from such a study. Some of the properties of plasma-polymerized thin films which have been measured include electrical conductivity, tunneling phenomena and photoconductivity, capacitance, optical constants, structure (IR absorption and ESCA), surface tension, free radical density (ESR), surface topography and reverse osmosis characteristics. So far relatively few of these measurements were made with the objective of determining mechanisms of plasma polymerization. The motivation in most instances was a specific application of the thin films. Considerable emphasis on correlations between mass spectroscopy in polymerizing plasmas and ESCA on polymer films with plasma polymerization mechanisms will be given later in this chapter based on recent work done in this laboratory. 

Cleavage of B3H7 -0(CH3)2 by PF3 occurs slowly at —16° 125,126) The major product, B2H4(PF3)2, is very reactive and is potentially a very useful reagent for synthesis. This novel diborane(4) adduct melts at —114.3° and decomposes by a second-order process. It was characterized by vapor density, infra-red spectroscopy and mass spectroscopy. Acid hydrolysis produced about four moles of H2 and basic hydrolysis produced about five moles of H2 per mole of B2H4(PF3)2. In addition, the following reactions were found to proceed nearly quantitatively. 

In essence, the test battery should include XRPD to characterize crystallinity of excipients, moisture analysis to confirm crystallinity and hydration state of excipients, bulk density to ensure reproducibility in the blending process, and particle size distribution to ensure consistent mixing and compaction of powder blends. Often three-point PSD limits are needed for excipients. Also, morphic forms of excipients should be clearly specified and controlled as changes may impact powder flow and compactibility of blends. XRPD, DSC, SEM, and FTIR spectroscopy techniques may often be applied to characterize and control polymorphic and hydrate composition critical to the function of the excipients. Additionally, moisture sorption studies, Raman mapping, surface area analysis, particle size analysis, and KF analysis may show whether excipients possess the desired polymorphic state and whether significant amounts of amorphous components are present. Together, these studies will ensure lotto-lot consistency in the physical properties that assure flow, compaction, minimal segregation, and compunction ability of excipients used in low-dose formulations. 

Plasma diagnostics consists of tools that can be used to characterize the plasma and thus provide information on the processes that are occurring with the plasma etcher. The main tools employed are spectroscopy, emission spectroscopy, mass spectrometry, and plasma probes. A detailed discussion on how each tool works is beyond the scope of this review. However, these tools are used to identify the species present in the plasma etcher, determine the temperature of the species, and determine the electron density. 

Several surface characterization techniques are used to monitor the latex cleaning process, among these are conductometric and potentiometric titrations, IR spectroscopy, electrophoresis and titration with a surface-active substance (see ref. 18 and references therein). Both in potentiometric and conductometric titrations even small traces of CO2 can lead to eironeous results [18]. In general the surface charge density is followed as a function of the cleaning process [23]. 

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