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In Situ Measurement Of Three-Dimensional Ion Densities In Focused Femtosecond Pulses, James Strohaber, Cornelis J. Uiterwaal
In Situ Measurement Of Three-Dimensional Ion Densities In Focused Femtosecond Pulses, James Strohaber, Cornelis J. Uiterwaal
Department of Physics and Astronomy: Dissertations, Theses, and Student Research
We image spatial distribution of xenon ions in the focus of a laser beam of ultrashort, intense pulses in all three dimensions, with a resolution of three by twelve microns in the two transverse directions. This allows for studying ionization processes without spatially averaging ion yields. Our in situ ion imaging is also useful to analyze focal intensity profiles and to investigate the transverse modal purity of tightly focused beams of complex light. As an example, the intensity profile of a Hermite-Gaussian beam mode HG recorded with ions is found to be in good agreement with optical images.
Nanoscale Investigation Of Polarization Interaction And Polarization Switching In Ferroelectric P(Vdf-Trfe) Copolymer Samples, Jihee Kim
Department of Physics and Astronomy: Dissertations, Theses, and Student Research
Ferroelectric properties of thin films and self-assembly of copolymers of polyvinylidene fluoride with trifluoroethylene (P(VDF-TrFE) have been studied. All samples were fabricated with Langmuir-Blodegtt (LB) film deposition technique. Two main observations are presented in this dissertation. One is a polarization interaction effect in multi-layered thin films made of two different copolymers, and the other is local polarization switching of the self-assembly, called nanomesas.
The multilayer films were built with two different content ratio of P(VDF-TrFE) copolymers. They were P(VDF-TrFE 80:20) and P(VDF-TrFE 50:50) with phase transition temperatures of 133 ± 4 ºC and 70 ± 4 ºC respectively. The polarization …