Academic literature on the topic 'Microprobe analysis'

This thesis is concerned with the application of Laser Microprobe Mass Spectrometry (LAMMS) to the microanalysis of inorganic materials and in particular to the quantification of such analyses. The investigation consists both of an assessment of the capabilities of a LAMMS instrument, the Cambridge Mass Spectrometry LIMA 2A, and an attempt to correlate experimental results with theoretical predictions. The principles of the operation of a LAMMS instrument are discussed and a description of the LIMA 2A instrument is presented. A survey of the literature concerned with the interaction of a high-powered laser with a solid specimen to produce a plasma, the basis of the LAMMS technique, is included. Particular emphasis is given to the description of this interaction in terms of a model based on a local thermodynamic equilibrium (LTE) in the plasma. This model is applied to the conditions estimated to be produced in the LIMA instrument to make simple predictions of expected results. A discussion of the possible methods for converting LAMMS data into a quantitative analysis is given, along with a brief description of the statistical techniques used for data handling. Several model materials, principally chosen for their well-defined composition and known lateral homogeneity, are used in this work. These are single-crystal silicon, a binary copper-nickel alloy and three III-V semiconductors drawn from the Ga-In-As system. The effect of the instrument itself is investigated, with a view to establishing its contribution to the errors observed in the data. This is followed by an investigation of the variation of both the absolute and relative ion signals produced. The variations in the relative ion signals are then compared with the predictions of the LTE model in an attempt to establish its validity. This comparison is also used to estimate the conditions produced in the laser-induced plasma and their variation with specimen chemistry and laser power density. The general conclusions of the investigation are drawn together in a discussion of the preferred methods for the quantification of LAMMS data and the expected error in the resulting analysis. It is shown that, provided appropriate methods are used, the LAMMS technique can provide quantitative analyses with precisions of about 5-20%.

The use of nuclear microprobe techniques including: Particle induced x-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) for elemental analysis and quantitative elemental imaging of biological samples is especially useful in biological and biomedical research because of its high sensitivity for physiologically important trace elements or toxic heavy metals. The nuclear microprobe of the Ion Beam Modification and Analysis Laboratory (IBMAL) has been used to study the enhancement in metal uptake of two different plants. The roots of corn (Zea mays) have been analyzed to study the enhancement of iron uptake by adding Fe (II) or Fe (III) of different concentrations to the germinating medium of the seeds. The Fe uptake enhancement effect produced by lacing the germinating medium with carbon nanotubes has also been investigated. The aim of this investigation is to ensure not only high crop yield but also Fe-rich food products especially from calcareous soil which covers 30% of world’s agricultural land. The result will help reduce iron deficiency anemia, which has been identified as the leading nutritional disorder especially in developing countries by the World Health Organization. For the second plant, Mexican marigold (Tagetes erecta), the effect of an arbuscular mycorrhizal fungi (Glomus intraradices) for the improvement of lead-phytoremediation of lead contaminated soil has been investigated. Phytoremediation provides an environmentally safe technique of removing toxic heavy metals (like lead), which can find their way into human food, from lands contaminated by human activities like mining or by natural disasters like earthquakes. The roots of Mexican marigold have been analyzed to study the role of arbuscular mycorrhizal fungi in enhancement of lead uptake from the contaminated rhizosphere.

Thesis (DTech (Science))--Peninsula Technikon, Cape Town, 2003.<br>The impetus for the refinement and renewal of daily-used products has spurred international interest in investigating the small in homogeneities that might exist in these products. This interest has become an important part in the design philosophy, which is based on structural information gained by the analysis of these products. It is this drive that initiated the study to investigate the simultaneous use of novel nuclear analytical techniques such as micro proton induced X-ray emission( u-PlXE), micro proton induced gamma-ray emission (u-PlGE) and micro proton backscattering (u-RBS) to achieved a broader and yet deeper insight into the fine structure of products. The fundamental underlying physical principles of these techniques are discussed to gain in-depth knowledge on how to them to obtain the desired information. Also determined was the degree of accuracy that could be attained in the application of this knowledge. These principles were evaluated in conjunction with the instrumentation with which the applicability of these techniques could then be further extended. More so is the use of sophisticated software that facilitated the use of both physical and instrumental parameters. After describing the necessary implements to achieve this further know-how, products of industrial origin were investigated to determine in homogeneities that existed in those products and compared those theoretical values. The first application was made to ceramic-based sorption electrodes to be used in the purification of wastewater.

A nuclear microprobe, typically consisting of 2 - 4 quadrupole magnetic lenses and apertures serving as objective and a collimating divergence slits, focuses MeV ions to approximately 1 x 1 μm for modification and analysis of materials. Although far less utilized, electrostatic quadrupole fields similarly afford strong focusing of ions and have the added benefit of doing so independent of ion mass. Instead, electrostatic quadrupole focusing exhibits energy dependence on focusing ions. A heavy ion microprobe could extend the spatial resolution of conventional microprobe techniques to masses untenable by quadrupole magnetic fields. An electrostatic quadrupole doublet focusing system has been designed and constructed using several non-conventional methods and materials for a wide range of microprobe applications. The system was modeled using the software package "Propagate Rays and Aberrations by Matrices" which quantifies system specific parameters such as demagnification and intrinsic aberrations. Direct experimental verification was obtained for several of the parameters associated with the system. Details of the project and with specific applications of the system are presented.