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Stellar And Interstellar Origins Of Meteoritic Nanodiamonds, Josiah Lewis
Stellar And Interstellar Origins Of Meteoritic Nanodiamonds, Josiah Lewis
Arts & Sciences Electronic Theses and Dissertations
In 1987 presolar grains were first isolated from meteorites, opening up a new line of data about the stars that produced them. Based on anomalies in isotopic ratios, identification and classification of presolar grains has borne great fruit in understanding nucleosynthesis, stellar evolution, and mass loss from the stellar objects in which these grains originated: primarily, but not exclusively, supernovae and asymptotic giant branch stars.Meteoritic nanodiamonds were the first type of presolar grain identified, but more than three decades later, their origins remain unclear. Anomalies in the ratios of Xe isotopes carried by the nanodiamonds suggest the nanodiamonds formed from …
Correlated Nanosims, Tem, And Xanes Studies Of Presolar Grains, Evan Edward Groopman
Correlated Nanosims, Tem, And Xanes Studies Of Presolar Grains, Evan Edward Groopman
Arts & Sciences Electronic Theses and Dissertations
The objective of this thesis is to describe the correlated study of individual presolar grains via Nano-scale Secondary Ion Mass Spectrometry (NanoSIMS), Transmission Electron Microscopy (TEM), and Scanning Transmission X-ray Microscopy (STXM) utilizing X-ray Absorption Near Edge Structure (XANES), with a focus on connecting these correlated laboratory studies to astrophysical phenomena. The correlated isotopic, chemical, and microstructural studies of individual presolar grains provide the most detailed description of their formation environments, and help to inform astrophysical models and observations of stellar objects.
As a part of this thesis I have developed and improved upon laboratory techniques for micromanipulating presolar grains …