PART 1 A new method has been used to suppress the undesirable Compton electrons ordinarily present in photoelectron spectra. As much as 90% of the Compton electron intensity was removed. This was accomplished by electronic cancellation of the individual Compton electrons. The method has been used with a thin lens type of spectrometer and has made possible the detection of new gamma rays at .391, .857 and 1.00 Mev. in Ra(B + C), at 1.01 Mev. in Ta¹⁸², and at .472 and .843 Mev. In Sb¹²⁴. No.new gamma rays were observed from Co⁶⁰. PART 2 A search for double beta decay in Sn¹²⁴ has been made using a coincidence technique particularly suited to double beta decay under the Majorana form of neutrino theory. Negative results were obtained and a lower limit of 0.3 - 0.7 x 10¹⁷ years has been set on the half-life of the process. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Photoelectric mixing in a photodiode is used In this work as a statistical spectroscopic tool. A number of experiments were performed to determine the fluctuation spectrum generated by this process and the statistical properties of the light which might be deduced from the data. Due to practical limitations in attainable temperatures, blackbody sources were not able to produce an observable mixing above shot noise. Experiments were also carried out using line spectra from gas discharge lamps. The best source available was a 300 W Xenon lamp, emitting lines in the red, which under optimum conditions produced excess current fluctuations equal to 60% of shot noise. The observation of photoelectric mixing losing a gas laser source has already been reported in the literature, but the Gaussian distributed electric field model usually applied does not fit the experimental results. A new model was proposed in this thesis which considers the laser light as a narrow band of coherent light embedded in a relatively broad band of spontaneous light. Mixing between the signal and the spontaneous emission was considered to be the only observable effect due to experimental limitations. This model appeared to fit the data and gave some information about the statistical properties of the laser beam. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Recently there has been considerable interest in studying the interactions of orbitals which were formerly thought of as localized and isolated. The technique of Photoelectron Spectroscopy (PES) is well suited for this and PE spectra are presented here for the series of five membered ring molecules consisting of tetrahydrofuran, γ-butyrolactone, 2,5-dihydrofuran, γ-crotonolactone, 1,3-dioxolane, ethylene carbonate, vinylene carbonate, 4-cyclopentene 1,3-dione, maleimide and maleic anhydride. In these spectra the IP's of the carbonyl oxygen lone pairs and the higher π levels have been assigned and trends in these IP's established in the series. For the carbonyl oxygen lone pair, the shift in IP caused by various groups (oxygen atoms α to the carbonyl, double bonds in the ring and additional carbonyl groups β to the one in question) are found to be approximately additive, which suggests that inductive effects are important. However, the pattern of π IP's must be rationalized in terms of both inductive and resonance effects. Finally some correlations with UV spectra for the last three molecules are presented. / Science, Faculty of / Chemistry, Department of / Graduate

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Photoelectron spectroscopy is the study of the kinetic energies of the photoelectrons ejected from gaseous species by monochromatic radiation. Subtraction of these kinetic energies from the incident photon energy yields the binding energies of the orbitals from which the electrons were removed. The work to be described falls into two main parts. The first is concerned with the development of a new type of spectrometer to measure such kinetic energies. To date, all photoelectron spectrometers designed specifically for gaseous samples have employed a retarding field of cylindrical geometry to energy-analyze the emitted photoelectrons. Consideration of the angular distribution with which electrons are ejected during the photoionization process indicates that a spectrometer utilizing a retarding field of spherical geometry should give a stopping curve, the first differential of which is close to the true photoelectron kinetic energy spectrum. Instruments of both cylindrical and spherical geometry were constructed and their properties tested. Conclusive evidence for the superiority of the spherical system is presented together with details of its construction and operation. The second part of this thesis/contains the results of photoelectron spectroscopic studies on twenty-one atoms and molecules (Ar, Kr, Xe, H₂, HD, D₂, N₂, CO, O₂, NO, HF, HCl , HBr, HI, F₂, Cl₂, Br₂, I₂,N₂O, NO₂ and NH₃). The energies of the ionic states could be obtained to a precision of 0.01 ev., and they agree, well with available spectroscopic data. In many instances new ionic states are found, and where possible they are correlated with states predicted by molecular orbital theory. Relative transition probabilities to the various ionic states are also obtained by this method. They are, in nearly every case, the only experimental values available. The spacings and relative probabilities for formation of ionic vibrational levels have been measured for certain states in H₂, HD, D₂, N₂, CO, O₂, NO, F₂, N₂O and NO₂ and the values obtained compared with spectroscopic and calculated data where this is available. / Science, Faculty of / Chemistry, Department of / Graduate

An organic Schottky barrier cell, consisting of a thin layer of the organic semiconductor, GaPc-Cl, in contact with gold on one side and an electrolyte containing a redox couple on the other, was developed as a solar energy conversion device. Schottky barriers were formed at both interfaces. Film morphology, as determined by the sublimation rate, was the major determinant of the photoelectrochemical behavior. An optimum film consisted of a single layer of crystallites about 1.0 micron in thickness, tightly packed together to give a non-porous film. Thinner films did not develop the full theoretical photopotential, and pores acted as recombination sites, decreasing the efficiency. Both negative and positive photopotentials could be developed, depending on the redox couple used. The photopotential, was found to be proportional to the differences between the Fermi level of the Au and the formal potential of the redox couple. Hydrogen evolution was possible with up to 0.1% solar efficiency on a platinized version of the optimum electrode. Results from photocurrent action spectra and pulsed laser photocoulostatics, showed the potential drop across the film was not linear, but formed a potential well about 0.1 eV deep, which captured charge carriers and decreased the efficiency. From scanning electron microscope studies, phthalocyanines, such as AlPc-Cl, GaPc-Cl, and InPc-Cl, with bulky anions were found to form block-like crystal structures favorable for use in Schottky barrier cells. Phthalocyanines with transition metals in the +2 oxidation state, such as FePc and MgPc, were found to form long needles, which were not favorable for use in Schottky barrier cells.

Call number: LD2668 .T4 1958 F79 / Master of Science

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Syed Ismat Shah, Dept. of Materials Science. Includes bibliographical references.