Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 86-88).

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 111-114).

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The one-boson-exchange potential model is studied in some detail. The parameters of a velocity-dependent potential based on such a model are fitted to reproduce two-body scattering data. This potential is then used in nuclear matter calculations by means of the reference spectrum method. It is shown that the average binding energy of a nucleon in nuclear matter and the saturation density are in reasonable agreement with the experimental values. / Thesis / Doctor of Philosophy (PhD)

Οι προσμίξεις παίζουν ένα σημαντικό ρόλο σε διάφορες φυσικές ιδιότητες όπως οι οπτικές, ηλεκτρικές, και σε φαινόμενα μεταφοράς. Η μελέτη των καταστάσεων υδρογονοειδών προσμίξεων είναι ένα από τα κύρια προβλήματα σε ημιαγώγιμα χαμηλοδιάστατα συστήματα επειδή η παρουσία τους επηρεάζει σημαντικώς την κινητικότητα των ηλεκτρονίων και τις οπτικές ιδιότητες. Έτσι, τα προηγούμενα χρόνια, πολλές θεωρητικές και πειραματικές έρευνες έχουν πραγματοποιηθεί για τη διερεύνηση των καταστάσεων πρόσμιξης σε χαμηλοδιάστατες κβαντικές δομές, όπως κβαντικά πηγάδια και κβαντικά καλώδια. Προσφάτως, οι καταστάσεις πρόσμιξης σε μηδενικής διάστασης συστήματα, όπως συσσωματώματα, μικροκρυσταλλίτες, νανοράβδους και κβαντικές τελείες έχουν προσελκύσει μεγάλο ενδιαφέρον. Ωστόσο, υπάρχουν λίγες μελέτες που διερευνούν τη συμπεριφορά προσμίξεων που βρίσκονται στην επιφάνεια νανοκρυστάλλων στα πλαίσια της προσέγγισης της ενεργού μάζας. Ο σκοπός της παρούσας εργασίας είναι η διερεύνηση της επίδρασης ενός μαγνητικού κι ενός ηλεκτρικού πεδίου αλλά και της υδροστατικής πίεσης πάνω στην ενέργεια σύνδεσης της θεμελιώδους κατάστασης μιας υδρογονοειδούς πρόσμιξης που εντοπίζεται στην επιφάνεια μιας ημιαγώγιμης κβαντικής τελείας. Οι υπολογισμοί βασίστηκαν στη μέθοδο μορφοποίησης δυναμικού, μια ακριβή αριθμητική μέθοδο που έχει αναπτυχθεί για να λύνει τη χρονο-ανεξάρτητη εξίσωση Schro ̈dinger για οποιοδήποτε αυθαίρετο δυναμικό αλληλεπίδρασης. Το κεφάλαιο 1 είναι η εισαγωγή της εργασίας, το κεφάλαιο 2 εξηγεί τις μεθόδους επίλυσης της εξίσωσης του Schro ̈dinger, ενώ το κεφάλαιο 3 περιγράφει τη θεωρία για ένα σύστημα σαν κι αυτό που χρησιμοποιήθηκε στην εργασία. Το κεφάλαιο 4 απεικονίζει τα αποτελέσματα σχετικά με την ενέργεια σύνδεσης της υδρογονοειδούς πρόσμιξης και τέλος το κεφάλαιο 5 κάνει αναφορά στα συμεράσματα που μπορούν να εξαχθούν. / Impurities play an elementary role in several physical properties like optical, electrical, and transport phenomena. The study of the hydrogenic impurity states is one of the main problems in semiconductor low dimensional systems because their presence influences greatly the electronic mobility and optical properties. Thus, in the past many years, much theoretical and experimental work is involved in investigating the impurity states in low dimensional quantum structures, such as quantum well (QW) and quantum well-wire (QWW). Recently, the impurity states in zero-dimensional (0D) systems, such as cluster, microcrystallines, nanorods, (NRs) and quantum dots (QDs) have drawn increasingly attentions. However, there are few works investigating the behavior of the impurities located at the surface of nanocrystals in the framework of effective-mass approximation. The purpose of the present work is to investigate the effect of a magnetic and electric field and hydrostatic pressure on the ground-state binding energy of a hydrogenic impurity located at the surface of a semiconductor QD. Calculations were based on the potential morphing method (PMM), an accurate numerical method which has been developed to solve the time independent Schro ̈dinger equation for any arbitrary interaction potential. Chapter 1 is the introduction of this project, chapter 2 explains the methods for solving the Schro ̈dinger equation, while chapter 3 describes the theory for a system like that used to this project. Chapter 4 shows the results on the binding energy of the hydrogenic impurity and finally chapter 5 makes reference to the conclusions that can be made.

Isotherms of one atom thick film of adsorption for propane on purified Hipco single-walled carbon nanotube were experimentally studied at 6 different temperatures ranging from 190K up to 280K. In these isotherm measurements, two substeps were clearly present at temperatures between 190K and 220K. For propane adsorption, two different groups of binding energy sites on the nanotubes were determined by the outcome. Also, we found that those substeps were gradually smearing as the temperature increases. These features of propane adsorption were compared to the same features that were present for the case of ethane and butane adsorption on the same sample. In comparison, high binding energy sites revealed by low pressure substeps were clearly visible in all the cases. However, the high pressure substep that represents a low binding energy site, external surface site, was smearing as carbon chain length of adsorbed alkanes increase. For the case of butane adsorption, the substep was not pronounced in the alkanes' isotherms at the relative temperatures. We also determined a decrease in the values of specific surface area of the nanotubes and an increase in the values of binding energies of alkanes on the substrate were increased as the sizes and lengths of linear carbon alkanes were increased.

The E01-011 experiment at Jefferson Laboratory (JLab) studied light-to-medium mass Lambda hypernuclei via the (e,e'K+) electroproduction reaction. Precise measurement of hypernuclear ground state masses and excitation energies provides information about the nature of hyperon-nucleon interactions. Until recently, hypernuclei were studied at accelerator facilities with intense pi+ and K- meson beams. The poor quality of these beams limited the resolution of the hypernuclear excitation energy spectra to about 1.5 MeV (FWHM). This resolution is not sufficient for resolving the rich structure observed in the excitation spectra. By using a high quality electron beam and employing a new high resolution spectrometer system, this study aims to improve the resolution to a few hundred keV with an absolute precision of about 100 keV for excitation energies. In this work the high-resolution excitation spectra of 12B-Lambda, 7He-Lambda, and 28Al-Lambda hypernuclei are presented. In an attempt to emphasize the presence of the core-excited states we introduced a novel likelihood approach to particle identification (PID) to serve as an alternative to the commonly used standard hard-cut PID. The new method resulted in almost identical missing mass spectra as obtained by the standard approach. An energy resolution of approximately 400-500 keV (FWHM) has been achieved, an unprecedented value in hypernuclear reaction spectroscopy. For 12B-Lambda the core-excited configuration has been clearly observed with significant statistics. The embedded Lambda hyperon increases the excitation energies of the 11B nuclear core by 0.5-1 MeV. The 7He-Lambda spectrum has been observed with significant statistics for the first time. The ground state is bound deeper by roughly 400 keV than currently predicted by theory. Indication for the core-excited doublet, which is unbound in the core itself, is observed. The measurement of 28Al-Lambda provides the first study of a d-shell hypernucleus with sub-MeV resolution. Discrepancies of up to 2 MeV between measured and theoretically predicted binding energies are found. Similar disagreement exists when comparing to the 28Si-Lambda mirror hypernucleus. Also the core-excited structure observed between the major s-, p- and d-shell Lambda orbits is not consistent with the available theoretical calculations. In conclusion, the discrepancies found in this study will provide valuable input for the further development of theoretical models.

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