The aim of this work was to find a correlation between the electrical, optical and microstructural properties of thin SiO2 layers containing group IV nanostructures produced by ion beam synthesis. The investigations were focused on two main topics: The electrical properties of Ge- and Si-rich oxide layers were studied in order to check their suitability for non-volatile memory applications. Secondly, photo- and electroluminescence (PL and EL) results of Ge-, Si/C- and Sn-rich SiO2 layers were compared to electrical properties to get a better understanding of the luminescence mechanism.

Fluorescence imaging has been increasingly relied upon as the method of choice for many biological and medical applications. As demands for more sensitive and higher resolution imaging are ever-increasing, it is critical that photostable, and robust fluorophores capable of delivering high emission rates are available. Fluorescent silver nanoclusters offer an attractive compromise between the photostability and brightness of quantum dots and the compact versatility of organic chromophores. They have been shown to be superior in many roles, including as single molecule fluorophores and bulk multiphoton biological staining agents. The two-photon absorption cross sections are several orders of magnitude larger than commercially-available dyes, and they have demonstrated superior photostability under high intensity irradiation. In addition to the endogenous effects of the cluster, its small size of only a few atoms renders it highly susceptible to surface and environmental effects, which manifests, for example, in the observed photoinduced charge transfer between the silver cluster and oligonucleotide. This state has been shown to be highly advantageous in imaging applications, as control of this state enables better control over the time-averaged emission rate of the molecule. The mechanism of charge transfer, and the possible means by which this state can be controlled will be also be investigated in this work.

The aim of this work was to find a correlation between the electrical, optical and microstructural properties of thin SiO2 layers containing group IV nanostructures produced by ion beam synthesis. The investigations were focused on two main topics: The electrical properties of Ge- and Si-rich oxide layers were studied in order to check their suitability for non-volatile memory applications. Secondly, photo- and electroluminescence (PL and EL) results of Ge-, Si/C- and Sn-rich SiO2 layers were compared to electrical properties to get a better understanding of the luminescence mechanism.

Anthrax spores, in weaponized form, are dangerous biological warfare agents. Handheld technology for the rapid detection of anthrax is greatly needed to improve national security. Methods to detect anthrax spores are diverse, with most taking at least an hour for positive identification. A viable option for rapid detection is analytical pyrolysis (AP), which produces chemicals containing taxonomical information (biomarkers). AP methods are reviewed and critically analyzed to show that reproducible detection of anthrax spores in a rapid manner (< 5 min) with a handheld device is not currently possible. A promising alternative to AP is the use of a catalyst to produce biomarkers from anthrax spores with improved selectivity and reproducibility. Catalytic materials having promise for this include platinum, nickel, and superacids. Experiments evaluating several of these materials are described. A biomarker mass spectral library was created, based on information available in the scientific literature, to facilitate analysis and identification of the biomarkers produced experimentally. The RAMFAC algorithm was used to deconvolute chromatographic peaks to produce clean mass spectra and match them against entries in the biomarker library. While the library is not complete, its use with the RAMFAC algorithm enabled detection of many important biomarkers in experiments involving catalytic breakdown of anthrax spores. Experimental results from preliminary tests of several catalysts are presented and discussed. Addition of catalysts in the form of platinum nanoclusters and superacids to bacterial spores in a commercial pyrolyzer effected an increase in the amount of biomarkers produced at mild conditions over traditional pyrolysis methods. Electroformed nickel mesh, on the other hand, demonstrated low catalytic activity for the production of biomarkers, likely due to poor contact of the spores with the mesh. Biomarkers similar to those published in the literature were observed, including dipicolinic acid, picolinic acid, propionamide, acetamide, diketopiperazines, fatty acids, furfuryl alcohol, and DNA bases. A statistically designed factorial study was used to determine the importance of temperature, spore loading, and nanocluster loading on the production of three important biomarkers. The relative importance of these variables differs for each of the three important biomarkers, suggesting they are produced by different reaction mechanisms.

No description available.

In this thesis, the superconductive and superresistive properties of thin percolating films of lead nanoclusters are presented. The samples were created by depositing clusters from an inert gas aggregation cluster source onto substrates held at either room temperature or 10K. Observations of the characteristic behaviours of the samples were made through R(T ) and V (I) measurements. Several interesting features were observed - smooth and discrete steps in the R(I) curves, hysteresis between increasing and decreasing bias currents, and non-zero resistances at superconducting temperatures. Explanations are proposed in terms of theoretical models of several phenomena - phase slips, phase slip centres and hotspots - which have seen little prior application to percolating systems in literature.

The static equilibrium isothermal sorption of dioxane, ethyl acetate, and methanol vapors by POM polyoxometalates with the structure of buckyball (Mo132, Mo72Fe30) and torus (Mo138), and also polymer-salt compositions containing POM were studied. The changes in the chemical potentials of the components and the Gibbs energy of the interaction of POMs, polymers, and compositions with low molecular weight liquids are calculated. The Gibbs energies and entropies of interaction of the components of the POM – polymer systems are estimated. The stability of the POM structure before and after sorption was investigated by IR spectroscopy. It was established that all investigated POMs exhibit the highest sorption capacity for dioxane, the lowest for ethyl acetate. Mo132 exhibits maximum affinity for sorbates, Mo72Fe30 exhibits a minimum affinity, and Mo138 occupies an intermediate position. It was established that PVP and PVA adsorb methanol in significantly larger quantities compared with compositions containing POM. The same rule is observed for PVP-POM systems in the case of dioxane. PVA practically does not absorb dioxane, but the introduction of POM in films of polyvinyl alcohol leads to the appearance of the sorption ability of the film. For all compositions a decrease in the Gibbs energy of the interaction of components and an increase in entropy were found, which can be associated with loosening and partial destruction of the crystal structure of the POM when polymer chains are introduced into it. The structure of polyoxomolybdates was found to be stable in dioxane vapors, and is also preserved in polymer-salt compositions before and after sorption. / Изучена статическая равновесная изотермическая сорбция паров диоксана, этилацетата и метанола полиоксометаллатами ПОМ со структурой букибола (Mo132, Mo72Fe30) и тора (Mo138), а также полимерно-солевыми композициями, содержащими ПОМ. Рассчитаны изменения химических потенциалов компонентов и энергии Гиббса взаимодействия ПОМов, полимеров, композиций с низкомолекулярными жидкостями. Оценены энергии Гиббса и энтропии взаимодействия компонентов систем ПОМ – полимер. Методами ИК- спектроскопии исследована стабильность структуры ПОМ до и после сорбции. Установлено, что наибольшую сорбционную способность все исследованные ПОМ проявляют к диоксану, наименьшую – к этилацетату. Максимальное сродство к сорбатам проявляет Mo132, минимальное – Mo72Fe30, Mo138 занимает промежуточное положение. Установлено, что ПВП и ПВС сорбируют метанол в существенно больших количествах по сравнению с композициями, содержащие ПОМ. Такая же закономерность наблюдается для систем ПВП – ПОМ в случае диоксана. ПВС практически не поглощает диоксан, но введение ПОМ в пленки поливинилового спирта приводит к возникновению сорбционной способности пленки. Для всех композиций ПОМ -полимер обнаружено уменьшение энергии Гиббса взаимодействия компонентов и возрастание энтропии, которое может быть связно с разрыхлением и частичным разрушением кристаллической структуры ПОМ при внедрении в нее полимерных цепей. Обнаружено, что структура полиоксомолибдатов стабильна в парах диоксана, а также сохраняется в полимерно-солевых композициях до и после сорбции.

Plasmonic properties and the related novel applications are studied on various types of metallic nano-structures in one, two, or three dimensions. For 1D nanostructure, the motion of free electrons in a metal-film with nanoscale thickness is confined in its normal dimension and free in the other two. Describing the free-electron motion at metal-dielectric surfaces, surface plasmon polariton (SPP) is an elementary excitation of such motions and is well known. When further perforated with periodic array of holes, periodicity will introduce degeneracy, incur energy-level splitting, and facilitate the coupling between free-space photon and SPP. We applied this concept to achieve a plasmonic perfect absorber. The experimentally observed reflection dip splitting is qualitatively explained by a perturbation theory based on the above concept. If confined in 2D, the nanostructures become nanowires that intrigue a broad range of research interests. We performed various studies on the resonance and propagation of metal nanowires with different materials, cross-sectional shapes and form factors, in passive or active medium, in support of corresponding experimental works. Finite- Difference Time-Domain (FDTD) simulations show that simulated results agrees well with experiments and makes fundamental mode analysis possible. Confined in 3D, the electron motions in a single metal nanoparticle (NP) leads to localized surface plasmon resonance (LSPR) that enables another novel and important application: plasmon-heating. By exciting the LSPR of a gold particle embedded in liquid, the excited plasmon will decay into heat in the particle and will heat up the surrounding liquid eventually. With sufficient exciting optical intensity, the heat transfer from NP to liquid will undergo an explosive process and make a vapor envelop: nanobubble. We characterized the size, pressure and temperature of the nanobubble by a simple model relying on Mie calculations and continuous medium assumption. A novel effective medium method is also developed to replace the role of Mie calculations. The characterized temperature is in excellent agreement with that by Raman scattering. If fabricated in an ordered cluster, NPs exhibit double-resonance features and the double Fano-resonant structure is demonstrated to most enhance the four-wave mixing efficiency.