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dc.contributor.advisorSchweikert, Emile A.
dc.creatorRickman, Richard Dale
dc.date.accessioned2004-09-30T02:07:36Z
dc.date.available2004-09-30T02:07:36Z
dc.date.created2006-05
dc.date.issued2004-09-30
dc.identifier.urihttps://hdl.handle.net/1969.1/520
dc.description.abstractSome collision cascades, induced by keV polyatomic projectiles, result in the emission of multiple secondary ions. Such co-emissions imply that the ejecta originate from molecules co-located within the nano-volume perturbed by a single projectile impact. The relevance for the chemical analysis of nano-domains depends on the effectiveness of the projectile to cause co-emission of two or more secondary ions. This research examines how projectile characteristics, i.e. the energy and number of constituent atoms in the projectile, influence multiple secondary ion emission, or "superefficient" events. In addition we examine the relevance of this technique for nanostructure investigation. Yields have been measured for multi-ion emission events as a function of projectile characteristics. The data show that some collision cascades are "superefficient". For example, in a four-ion emission event, the yield for the phenylalanine quasi-molecular ion is two orders of magnitude larger from Au4+ impacts than from equal velocity Au+ projectiles. Yields for the co-emission of two phenylalanine quasi-molecular ions from "super-efficient" events have been measured. This case is particularly productive in that the detection of two analytically significant ions is recorded from a single event. Large increases (one to two orders of magnitude) in co-emitted ion yields were observed with increasing projectile energy and complexity. Correlation coefficients were calculated for the co-emission of two Ph ions, their behavior suggests differences in emission pathways for bombardment by atomic and polyatomic projectiles. Finally, we use this methodology to investigate surface structural effects on the occurrence of "super-efficient" events. The results indicate that it is possible to distinguish between two phases of a chemical compound although the stoichiometry remains the same. These results confirm previous predictions concerning the chemical nature of these "super-efficient" events. Also shown is that they are sensitive to the surface nanoenvironment. This approach extends the technology of Secondary Ion Mass Spectrometry by providing a methodology for probing surface nano-domains at the sub100 nm level.en
dc.format.extent12396863 bytesen
dc.format.extent316305 bytesen
dc.format.mediumelectronicen
dc.format.mimetypeapplication/pdf
dc.format.mimetypetext/plain
dc.language.isoen_US
dc.publisherTexas A&M University
dc.subjectSIMSen
dc.subjectPolyatomic Projectilesen
dc.subjectMultiple Ion Emission Eventsen
dc.subjectEvent-by-Eventen
dc.subjectSurface Characterizationen
dc.titleSecondary ion emission from “super-efficient” events: prospects for surface mass spectrometryen
dc.typeBooken
dc.typeThesisen
thesis.degree.departmentChemistryen
thesis.degree.disciplineChemistryen
thesis.degree.grantorTexas A&M Universityen
thesis.degree.nameDoctor of Philosophyen
thesis.degree.levelDoctoralen
dc.contributor.committeeMemberRowe, Marvin W.
dc.contributor.committeeMemberVigh, Gyula
dc.contributor.committeeMemberHart, Ronnie
dc.type.genreElectronic Dissertationen
dc.type.materialtexten
dc.format.digitalOriginborn digitalen


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