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theses

The development of novel materials has been central to enabling technological change that has affected humankind in many positive ways, and a few negative ones. From the utilization primitive stone tools to the smelting of iron and other metals to the introduction of semiconductor devices we continuously bring new materials and devices into everyday life. Their introduction has been accelerating during the past century, in part because of our much more sophisticated understanding of the basic atomic scale nature of materials. Today, the development of new material requires that we fully understand their atomic composition and structure and the unique properties that they may hold: mechanical, electronic, magnetic, optical, etc. This understanding requires that we employ sophisticated atomic scale characterization techniques. Helium Ion Microscopy (HIM) is one such technique, a novel microscopy method introduced over the past decade that empowers researcher not only to image sample surfaces with sub-nanometer resolution but to directly probe insulating samples. This thesis introduces the new technique of Helium Ion Microscopy and demonstrates its use in a few rather different applications. It also describes a new method that we developed to enable nanoscale elemental analysis. Direct visualization of previously inaccessible insulating samples has enabled us to image the nanoscale effects of a newly discovered drug. A series of images offers a vivid set of evidence of restoration of ischemia damaged kidney structures in rats. In another study we proposed a new mechanism for the growth of coral calcium carbonate skeletons, where (in combination with several other analytical tools) Helium Ion Microscopy produced images not only of excellent scientific value but also of high aesthetic beauty as acknowledged by publications in Science, Nature, and the New York Times. We have further helped the development of Helium Ion Microscopy by introducing a new method of in-situ elemental analysis. Based on a time of flight principle, our novel detector system is capable of providing compositional analysis of samples in additional to high-resolution imaging (essentially nano-scale Rutherford backscattering). Working in the 30 keV He+ energy regime, our time of flight detector system collects backscattered He particles, then by measuring the energy loss that occurs during the backscattering process we can identify the elements in the target. This is a substantially more sensitive and quantitative technique with higher spatial resolution compared to Energy Dispersive X-ray spectroscopy in SEMs, the most important established technique.

ETD_8865

Ph.D.

Includes bibliographical references

by Viacheslav Manichev

doi:10.7282/T3PN992W

ETD doctoral

The author owns the copyright to this work.