Energy, Angular and Charge Deposition Dependence of Electron Transmission through Insulating Polyethylene Terephthalate Nanocapillaries for Narrow Beam Production
Date of Award
Doctor of Philosophy
Dr. John A. Tanis
Dr. Asghar Kayani
Dr. Thomas Gorczyca
Dr. Nikolaus Stolterfoht
Nanocapillary, guiding, charge deposition, transmission. elastic. inelastic
This study analyzes the characteristic properties of electron transmission with incident energies of 300, 500 and 800 eV for the production of nanometer-sized beams through insulating polyethylene terephthalate (PET) nanocapillaries. More specifically, it investigates the transmission for very small tilt angles near zero degrees with the small step sizes revealing distinct regions of behavior, angular dependence, energy and the charge deposition dependence on transmission. Results were obtained for two Samples, 1 and 2, with different capillary diameters (100/200 nm) and pore densities (5 x 108 /5 x 107 /cm2), respectively, with the same foil thickness 12 μm. It is observed that the two regions of transmission for both samples corresponding to direct and guided electrons, as well as the transition region between them, are dependent on the sample tilt angle. The angular and energy dependence results for both samples agree well despite the differences in capillary diameters and pore densities. Investigations of the charge deposition dependence of electrons passing through PET nanocapillary foils for the two samples under the same conditions are discussed in this study. Different results occurred for the two samples, with Sample 1 showing a time dependence on the transmission having a fast rise some time after putting the beam onto the capillaries and then reaching equilibrium quite quickly. The results for tilt angles larger than zero degrees (up to +2.5o) reveal that the electron transmission is inelastic when the transmission reaches equilibrium. In contrast, for Sample 2, it is observed that the electrons are transmitted without delay; however, the input current density is more than an order of magnitude larger than for Sample 1. Additionally, it is observed for Sample 2 that a rather fast decrease of the intensity occurs until the transmission attains its equilibrium. The difference in results is discussed in terms of the current density difference for the two samples leading to the blocking effect, a decrease of intensity or zero intensity, from the primary charge patch due to the overcharging of the sample.
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Keerthisinghe, Darshika, "Energy, Angular and Charge Deposition Dependence of Electron Transmission through Insulating Polyethylene Terephthalate Nanocapillaries for Narrow Beam Production" (2015). Dissertations. 546.