{"id":{"repo_id":"njit","oai_identifier":"oai:digitalcommons.njit.edu:dissertations-1344"},"canonical_url":"https://search.dev.ndltd.org/etd/njit/oai:digitalcommons.njit.edu:dissertations-1344","repository":{"repo_id":"njit","name":"NJIT","base_url":"https://digitalcommons.njit.edu/do/oai/"},"display":{"title":"Development of x-ray holography methods for structure determination : Application of high speed detectors and novel numerical methods","abstract":"Holographic methods show much promise to enable direct determination of atomic structure with minimal assumptions and approximations. The approach can, in principle, provide three dimensional information on atomic positions. However, significant developments in experimental techniques, instrumentation and in data collection and analysis are needed. A review of the holography method is given with a focus on X-ray fluorescence holography. Methods for analysis of X-ray holographic data are also reviewed. An overview of the detectors relevant to X-ray measurements is also presented. An experimental apparatus for rapid acquisition of X-ray holographs using novel X-ray detectors has been developed. The integration of high speed detectors and the utilization of rapid sampling methods to produce high quality holograms form the core of this work. A new method for direct extraction of the electron charge density based on expansion of the hologram with respect to a spherical harmonic basis is developed. This approach attacks the problem of obtaining the electron density from the hologram by the introduction of periodic constraints (fixed unit cells) while maintaining flexibility by making no assumptions about the positions of atoms within the unit cells. Problems with local or long range distortions can be solved by utilizing cells of the appropriate size. The method makes no other assumptions. Model charge densities derived from this approach are shown to match quite well with the input model crystal structures with no need for heavy filtering typical of the Barton Transform. The algorithm can be fully automated and hence falls into the class of \"Direct Methods\". This new approach may move the method of X-ray holography from the developmental stage to a powerful and routine tool for the solution of single crystal structures relevant to inorganic materials and organic systems.","abstract_html":"Holographic methods show much promise to enable direct determination of atomic structure with minimal assumptions and approximations. The approach can, in principle, provide three dimensional information on atomic positions. However, significant developments in experimental techniques, instrumentation and in data collection and analysis are needed. A review of the holography method is given with a focus on X-ray fluorescence holography. Methods for analysis of X-ray holographic data are also reviewed. An overview of the detectors relevant to X-ray measurements is also presented. An experimental apparatus for rapid acquisition of X-ray holographs using novel X-ray detectors has been developed. The integration of high speed detectors and the utilization of rapid sampling methods to produce high quality holograms form the core of this work. A new method for direct extraction of the electron charge density based on expansion of the hologram with respect to a spherical harmonic basis is developed. This approach attacks the problem of obtaining the electron density from the hologram by the introduction of periodic constraints (fixed unit cells) while maintaining flexibility by making no assumptions about the positions of atoms within the unit cells. Problems with local or long range distortions can be solved by utilizing cells of the appropriate size. The method makes no other assumptions. Model charge densities derived from this approach are shown to match quite well with the input model crystal structures with no need for heavy filtering typical of the Barton Transform. The algorithm can be fully automated and hence falls into the class of "Direct Methods". This new approach may move the method of X-ray holography from the developmental stage to a powerful and routine tool for the solution of single crystal structures relevant to inorganic materials and organic systems.","abstract_has_math":false,"creators":["Wang, Yuhao"],"institution":null,"degree_name":"Doctor of Philosophy in Materials Science and Engineering - (Ph.D.)","degree_level":null,"degree_discipline":"Committee for the Interdisciplinary Program in Materials Science and Engineering","degree_department":null,"school":null,"contributors":["Trevor Tyson","Jianming Bai","Ken Keunhyuk Ahn"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-01-31T08:00:00Z","date_published":"2012-01-31T08:00:00Z","updated_at":"2026-07-24T03:22:14Z","subjects":["X-ray flourescence holography","Direct method","Multi-element detector","Crystal structure determination","Spherical harmonic analysis","Inverse problem","Materials Science and Engineering"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://digitalcommons.njit.edu/dissertations/289","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Trevor Tyson","Jianming Bai","Ken Keunhyuk Ahn"]},{"key":"dc:creator","label":"Author","values":["Wang, Yuhao"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Committee for the Interdisciplinary Program in Materials Science and Engineering"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy in Materials Science and Engineering - (Ph.D.)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["X-ray flourescence holography","Direct method","Multi-element detector","Crystal structure determination","Spherical harmonic analysis","Inverse problem","Materials Science and Engineering"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalcommons.njit.edu/dissertations/289"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Holographic methods show much promise to enable direct determination of atomic structure with minimal assumptions and approximations. The approach can, in principle, provide three dimensional information on atomic positions. However, significant developments in experimental techniques, instrumentation and in data collection and analysis are needed. A review of the holography method is given with a focus on X-ray fluorescence holography. Methods for analysis of X-ray holographic data are also reviewed. An overview of the detectors relevant to X-ray measurements is also presented. An experimental apparatus for rapid acquisition of X-ray holographs using novel X-ray detectors has been developed. The integration of high speed detectors and the utilization of rapid sampling methods to produce high quality holograms form the core of this work. A new method for direct extraction of the electron charge density based on expansion of the hologram with respect to a spherical harmonic basis is developed. This approach attacks the problem of obtaining the electron density from the hologram by the introduction of periodic constraints (fixed unit cells) while maintaining flexibility by making no assumptions about the positions of atoms within the unit cells. Problems with local or long range distortions can be solved by utilizing cells of the appropriate size. The method makes no other assumptions. Model charge densities derived from this approach are shown to match quite well with the input model crystal structures with no need for heavy filtering typical of the Barton Transform. The algorithm can be fully automated and hence falls into the class of \"Direct Methods\". This new approach may move the method of X-ray holography from the developmental stage to a powerful and routine tool for the solution of single crystal structures relevant to inorganic materials and organic systems."]},{"key":"dc:title","label":"Title","values":["Development of x-ray holography methods for structure determination : Application of high speed detectors and novel numerical methods"]}]}],"canonical_facts":{"dc:contributor":["Trevor Tyson","Jianming Bai","Ken Keunhyuk Ahn"],"dc:creator":["Wang, Yuhao"],"dc:description.abstract":["Holographic methods show much promise to enable direct determination of atomic structure with minimal assumptions and approximations. The approach can, in principle, provide three dimensional information on atomic positions. However, significant developments in experimental techniques, instrumentation and in data collection and analysis are needed. A review of the holography method is given with a focus on X-ray fluorescence holography. Methods for analysis of X-ray holographic data are also reviewed. An overview of the detectors relevant to X-ray measurements is also presented. An experimental apparatus for rapid acquisition of X-ray holographs using novel X-ray detectors has been developed. The integration of high speed detectors and the utilization of rapid sampling methods to produce high quality holograms form the core of this work. A new method for direct extraction of the electron charge density based on expansion of the hologram with respect to a spherical harmonic basis is developed. This approach attacks the problem of obtaining the electron density from the hologram by the introduction of periodic constraints (fixed unit cells) while maintaining flexibility by making no assumptions about the positions of atoms within the unit cells. Problems with local or long range distortions can be solved by utilizing cells of the appropriate size. The method makes no other assumptions. Model charge densities derived from this approach are shown to match quite well with the input model crystal structures with no need for heavy filtering typical of the Barton Transform. The algorithm can be fully automated and hence falls into the class of \"Direct Methods\". This new approach may move the method of X-ray holography from the developmental stage to a powerful and routine tool for the solution of single crystal structures relevant to inorganic materials and organic systems."],"dc:identifier":["https://digitalcommons.njit.edu/dissertations/289"],"dc:subject":["X-ray flourescence holography","Direct method","Multi-element detector","Crystal structure determination","Spherical harmonic analysis","Inverse problem","Materials Science and Engineering"],"dc:title":["Development of x-ray holography methods for structure determination : Application of high speed detectors and novel numerical methods"],"dc:type":["Dissertation"],"thesis:degree_discipline":["Committee for the Interdisciplinary Program in Materials Science and Engineering"],"thesis:degree_name":["Doctor of Philosophy in Materials Science and Engineering - (Ph.D.)"]},"updated_at":"2026-07-24T03:22:14Z"}