Illuminated metal nanoparticles (MNPs) feature collective electron oscillations (so-called localized surface plasmons or LSPs) which facilitate concentrating light-matter interactions to length scales below the diffraction limit. Part I of this book describes two applications of this confinement effect. Firstly, the use of single particles as optically active probes for scanning near-field optical microscopy is demonstrated. Secondly, fluorescence enhancement in the vicinity of a single MNP is described theoretically. This description focuses on how the particle diameter and the surrounding medium influence the enhancement. It turned out that in these two examples the optical signal levels can be improved by manipulating the spectral LSP resonance position of the particles. This finding triggered the search for a method allowing optical particle tuning. Part II of this thesis describes an approach which allows such a spectral LSP manipulation on the single-particle level. The method makes use of the optically induced reduction of metal salt complexes in solution, which leads to the deposition of thin layers of elemental metal onto single, intentionally addressed particles. The deposition process is monitored by optical LSP analysis, and thus the tuning of the optical particle properties is controlled in situ. With this technique, a manipulation of both the size and the shape of single nanoparticles was achieved. Initial experiences were gained by manipulating spherical and ellipsoidal gold particles, for which a red- and a blueshift of the LSP resonance was observed, respectively. The insights obtained from these experiments were then applied to tune the interparticle separation in nanoparticle pairs, i.e., to tune the resonance wavelength of these plasmonic nanoresonators. Subsequently, single resonators were used to reshape the fluorescence emission spectrum of organic molecules. Besides size and shape, also material parameters such as the surface roughness and the surface material composition influence the optical properties of MNPs. Both aspects are addressed using the example of rough platinum spheres and demonstrating the fabrication of bimetallic core-shell particles. As the material compositon of particles not only influences their optical, but for example also their catalytic or magnetic properties, photochemical metal deposition with in-situ optical LSP read-out builds a bridge to other fields of nanoscience. The presented method is a versatile tool for the fabrication and manipulation of nanostructures, and it is not limited to the field of plasmonics. / Metallische Nanopartikel (MNP) weisen unter Beleuchtung kollektive Schwingungen des Elektronengases auf (sogenannte lokalisierte Oberflächenplasmonen oder LOP). Die dadurch entstehende elektromagnetische Feldverteilung um die Partikel erlaubt die Konzentration von Licht-Materie-Wechselwirkungen auf einen Größenbereich unterhalb des Beugungslimits. In Teil I des vorliegenden Buches werden zwei Anwendungen dieses Konzentrationseffekts beschrieben. Zum einen wird die Verwendung eines einzelnen Partikels als Rastersonde für die optische Nahfeldmikroskopie gezeigt. Zum anderen wird die Fluoreszenzverstärkung in der unmittelbaren Umgebung eines Partikels untersucht. In letzterem Fall liegt der Fokus auf dem Einfluss der Partikelgröße und des Umgebungsmediums auf den Verstärkungsfaktor. Beide Untersuchungen zeigten, dass die Stärke der auftretenden optischen Signale von einer gezielten Steuerung der LOPResonanz profitieren kann. Diese Erkenntnis führte zur Entwicklung einer Methode, welche eine solche spektrale LOP-Steuerung erlaubt. Mit der in Teil II beschriebenen photochemischen Abscheidung von Metall auf einzelne Partikel wurde ein geeigneter Ansatz gefunden. Dabei wird die optisch induzierte Reduktion von Metallsalzkomplexen in einer Lösung ausgenutzt, um dünne Metallschichten auf gezielt ausgewählte Partikel aufzubringen. Der Abscheidungsprozess wird optisch über die Änderung der LOP-Resonanz des belichteten Partikels überwacht. Somit können dessen optische Eigenschaften gezielt in situ eingestellt werden. Mit der beschriebenen Technik können die Größe und die Form einzelner metallischer Partikel beeinflusst werden, was sich in einer Rot- bzw. Blauverschiebung der LOPResonanz äußert. Dieses Prinzip konnte zuerst an sphärischen und ellipsoidalen Goldpartikeln gezeigt werden. Die gewonnen Erkenntnisse wurden dann auf die gezielte Einstellung des Teilchenabstandes in Partikelpaaren übertragen, d. h., die Resonanzwellenlänge solcher plasmonischer Nanoresonatoren wurde gezielt manipuliert. Die Resonatoren konnten in einem zweiten Schritt zur Steuerung des Fluoreszenzspektrums organischer Moleküle eingesetzt werden. Neben Größe und Form spielen auch Materialparameter wie die Oberflächenrauigkeit und das Oberflächenmaterial eine wichtige Rolle für die optischen Eigenschaften der Partikel. Diese Parameter wurden am Beispiel von rauen Platinpartikeln sowie an bimetallischen Kern-Schale-Partikeln untersucht. Da das Oberflächenmaterial nicht nur die optischen, sondern z. B. auch katalytischen und magnetischen Eigenschaften der Partikel beeinflusst, verbindet die vorgestellte Methode die Plasmonik mit vielen anderen Bereichen der Nanotechnologie. Sie stellt eine vielseitige Technik zur Herstellung und Manipulation von Nanostrukturen dar, ohne dabei auf die Nanooptik limitiert zu sein.

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Two main subjects, ellipsometry and computer screen photo-assisted techniques (CSPT), form the main line in this thesis. Ellipsometry is an optical technique based on the detection of polarization changes of light upon interaction with a sample. As most optical detection techniques it is non-intrusive and an additional advantage is its high surface sensitivity: thickness resolution in the order of pm can in principle be achieved. Therefore, ellipsometry is widely used as a technique for determination of optical constants and layer thickness for thin-layer structures. Lately ellipsometry has also been proposed for sensing applications, utilizing the detection of changes in the properties of thin layers. One application is described in this thesis concerning the detection of volatile organic solvents in gas phase using modified porous silicon layers, fabricated by electrochemical etching of silicon to create nm-sized pores. This greatly increases the surface area, promoting gas detection because the number of adsorption sites increases. Other applications of ellipsometry discussed in this thesis are based on combination with CSPT. CSPT is a way to exploit existing optical techniques for use in low-cost applications. In CSPT the computer screen itself is used as a (programmable) light source for optical measurements. For detection a web camera can be used and the whole measurement platform is formed by the computer. Since computers are available almost everywhere, this is a promising way to create optical measurement techniques for widespread use, for example in home-diagnostics. Since the only thing that needs to be added is a sample holder governing the physical or chemical process and directing the light, the cost can be kept very low. First, the use of CSPT for the measurement of fluorescence is described. Fluorescence is used in many detection applications, usually by chemically attaching a fluorescent marker molecule to a suitable species in the process and monitoring the fluorescent emission. The detection of fluorescence is shown to be possible using CSPT, first in a cuvette-based setup, then using a custom designed micro array. In the latter, polarizers were used for contrast enhancement, which in turn led to the implementation of an existing idea to test CSPT for ellipsometry measurements. In a first demonstration, involving thickness measurement of silicon dioxide on silicon, a thickness resolution in the order of nm was already achieved. After improvement of the system, gradients in protein layers could be detected, opening the door toward biosensor applications. Some further development will be needed to make the CSPT applications described here ready for the market, but the results so far are certainly promising.

The aim of the present work was to design and fabricate all purpose, positioning-tolerant and efficient interconnects between single-mode fibers and integrated waveguides out of polymers. The developed structures are part of the optical packaging of integrated optical chips. Integrated optics have gathered tremendous interest throughout recent years from research as well as from the industry, and most likely the demand will further grow in the future. Today’s trend is to establish optical data communication not only in far-distance transmission but also in end-user or so called fiber-to-home configurations, or, in the near future, also on board or even chip level. In addition, integrated optical sensors are gaining more and more importance. In the future, lab-on-a-chip systems may be able to simplify and accelerate analysis methods within health care or allow for a continuous monitoring of almost any environmental variable. All these applications call for robust optical packaging solutions. Many integrated optical chips are using a silicon-on-insulator design. Technologies which were originally intended for the manufacturing of integrated circuits can be utilized for the fabrication of such silicon-on-insulator chips. Point-of-care testing, which is a considerable part of bio-sensing, in some cases only allows the use of disposable transducer elements. The fabrication of these transducers, also including almost all other system parts, may be possible using polymers. Alternative fabrication methods like nanoimprint lithography can be applied for the patterning of polymers. With these, the extension of already known working principles or even entirely new device architectures become feasible for mass production. The direct patterning of polymers by means of nanoimprint was used to fabricate interconnects for integrated waveguides. In contrast to conventional lithography approaches, where a patterned resist layer is used as a masking layer for subsequent process steps, direct patterning allows the immediate use of the structures as functional elements. Firstly, nanoimprint allows diffraction-unlimited patterning with nanometer resolutions as well as the replication of complex three-dimensional patterns. These unique properties were used within this work to pattern shallow gratings atop an integrated waveguide within only one single manufacturing step. The gratings are used as coupling elements and can be utilized either to couple light from external elements to the chip or vice versa. Considerations regarding the optical effects on single-mode polymer waveguides as well as grating couplers were obtained from simulation. They are specific to the chosen design and the used polymer and cannot be found elsewhere so far. Compared to similar designs and fabrication strategies proposed in literature, the ones followed here allow for a higher efficiency. The dimensions and process windows obtained from simulation did serve as a basis for the subsequent fabrication of the grating couplers. All steps which are necessary to turn the calculated design into reality, ranging from master fabrication, to working mold cast and imprint, are shown in detail. The use of a working mold strategy is of crucial importance for the fabrication process and is discussed in detail. The use of a working mold preserves a costly master and further allows for a cost-efficient production. Parameters which are relevant for the production as well as for the final polymer patterns were analyzed and discussed. On the basis of the obtained data, a process optimization was performed. The optical characterization was also part of the presented work. A comparison with the results obtained from simulation is included and additional effects were revealed. Most of them may be subject to further improvement in future designs. In summary, the present work contributes to the field of optical packaging. It shows a viable route for the design and fabrication of interconnects of single-mode polymer waveguides. The presented design can be used as a building block which can be placed at almost any positions within an integrated optical chip. The fabrication method includes a minimum number of process steps and is still able to increase performance compared to similar approaches. Moreover, all process steps allow for scaling and are potential candidates for mass production.

The thesis deals with the development and characterization of new light sources, which are mandatory for applications in atomic and molecular spectroscopy, medical and biological imaging or industrial production. For that purpose, the employment of interactions of high intensity ultra-short laser pulses with gaseous media offers a rich variety of physical effects which can be exploited. The effects are characterized by a nonlinear dependency on the present light fields. Therefore, accurate modeling of the nonlinearities of the gas is crucial. In general, the nonlinearities are due to the electronic response of the gas atoms to the light field and one distinguishes between the response of bound and ionized electrons. The first part investigates laser pulse self compression, where the consideration of a purely bound electron response is sufficient. We apply an exotic setup with an negative Kerr nonlinearity in order to avoid spatial collapse of the beam on the cost of dealing with an highly dispersive nonlinearity. Analytical analysis and numerical simulations prove the possibility of laser pulse compression in such setups and reveals a new compression scheme, where the usually disturbing dispersion of the nonlinaerity is responsible for compression. Dealing with tera-Hertz generation by focusing an ionizing two-color laser pulse into gas, the second part exploits a medium nonlinearity caused by ionized electrons. We reveal in a mixed analytical and numerical analysis the underlying physical mechanism for THz generation: ionized electrons build up a current, which radiates. Thereby, the the two-color nature of the input laser is crucial for the emitted radiation to be in the tera-Hertz range. Combining this physical model with a pulse propagation equation allows us to achieve remarkable agreement with experimental measurements. Finally, the third part deals with nonlinearities from bound as well from ionized electrons on a fundamental level. We advance beyond phenomenological models for responses of bound and ionized electrons and quantum mechanically model the interaction of an ultra-short laser pulse with a gas. Already the simplest case of one dimensional hydrogen reveals basic features. For low intensities, the Kerr nonlinearity excellently describes the response of bound electrons. For increasing intensity, ionization becomes important and the response from ionized electrons is the governing one for high intensities. This quantum mechanical correct modeling allows us to explain saturation and change of sing of the nonlinear refractive index and to deduce suited approximate models for optical nonlinearities.

The main aim of this thesis has been to contribute to the ongoing work with development of new diode-laser-based spectroscopic techniques and metho­do­lo­gies for sensitive detection of molecules in gas phase. The techniques under scrutiny are tunable diode laser absorption spectrometry (TDLAS) and Faraday modulation spectrometry (FAMOS). Conventional distributed-feedback (DFB) tele­communication diode lasers working in the near-infrared (NIR) region have been used for detection of carbon monoxide (CO) and temperature in hot humid media whereas a unique frequency-quadrupled external-cavity diode laser producing mW powers of continuous-wave (cw) light in the ultra violet (UV) region have been used for detection of nitric oxide (NO). A methodology for assessment of CO in hot humid media by DFB-TDLAS has been developed. By addressing a particular transition in its 2nd overtone band, and by use of a dual-fitting methodology with a single reference water spectrum for background correction, % concentrations of CO can be detected in media with tens of percent of H2O (≤40%) at T≤1000 °C with an accuracy of a few %. Moreover, using an ordinary DFB laser working in the C-band, a technique for assessment of the temperature in hot humid gases (T≤1000 °C) to within a fraction of a percent has been developed. The technique addresses two groups of lines in H2O that have a favorable temperature dependence and are easily accessed in a single scan, which makes it sturdy and useful for industrial applications. A technique for detection of NO on its strong electronic transitions by direct absorption spectrometry (DAS) using cw UV diode laser light has been deve­loped. Since the electronic transitions are ca. two or several orders of magnitude stronger than of those at various rotational-vibra­tional bands, the system is capable of detecting NO down to low ppb∙m concentrations solely using DAS. Also the FAMOS technique has been further developed. A new theoretical description expressed in terms of both the integrated line strength of the transition and 1st Fourier coefficients of a magnetic-field-modulated dispersive lineshape functions is presented. The description has been applied to both ro-vib Q-transitions and electronic transitions in NO. Simulations under different pressures and magnetic field conditions have been made that provide the optimum conditions for both cases. A first demonstration and characteri­zation of FAMOS of NO addressing its electronic transitions in the UV-region has been made, resulting in a detection limit of 10 ppb∙m. The characterization indicates that the technique can be significantly improved if optimum conditions can be obtained, which demonstrates the high potential of the UV-FAMOS technique.

Tez (Yüksek Lisans) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik ve Haberleşme Mühendisliği Anabilim Dalı, 2007. / Kaynakça var.

Kärnkraftsolyckan i Tjernobyl ledde till en spridning av radioaktiva ämnen över Europa och Sverige. År 2018 är det 32 år sedan kärnkraftsolyckan ägde rum och den enda radioaktiva isotopen som finns kvar i det svenska ekosystemet som följd av olyckan i en betydande mängd är Cs-137, på grund av dess 30-åriga halveringstid. Genom att bestämma aktiviteten hos svamp kan halten Cs-137 i mark uppskattas. Hösten 2018 kommer det tvärvetenskapliga massexperimentet Strålande jord att utföras i syfte att kartlägga denna halt i hela Sverige. Syftet med detta examensarbete var att nå resultat som är användbara vid aktivitetsbestämning av svamp. Ett numeriskt verktyg för analys av data ifrån gammaspektroskopi har konstruerats. Två metoder för att beräkna händelser (counts) i energitoppar i gammaemissionsspektra har formulerats och varit byggstenar för det vidare arbetet. Under arbetets gång har följande bestämts: effektiviteten hos en high purity germanium (HPGe) detektor, aktiviteten hos två svampprover, attenueringskoeffcienten av 662 keV-gamma för samma svampprover samt för vatten. För att kunna approximera en burk med svamp som en isotropt strålande punktkälla och få goda resultat behöver aktivitetsmätningarna göras med ett långt avstånd mellan provet och detektorn. Att mätningar måste göras på ett långt avstånd gör att approximationen bara är lämplig för ett svampprov med hög aktivitet, vilket blev tydligt i detta examensarbete då aktiviteten hos ett lågaktivt svampprov inte kunde bestämmas med god statistik trots att enskilda mätningar gjordes under närmare en veckas tid. Systematiska fel har inte tagits hänsyn till i detta arbete, utan enbart statistisk osäkerhet. / The nuclear disaster in Chernobyl brought radioactive substances over Europe and Sweden. In 2018 it has passed 32 years since the disaster and the only radioactive isotope that reamins in the swedish ecosystem at a signicant level is Cs-137. By determining activity of mushroom, the amount of Cs-137 in the ground can be estimated. In the fall of 2018, the interdisciplinary mass-experiment Strålande jord will take place with the purpose to map this amount all over Sweden. The purpose of this work was to reach results that could be of use when determining the activity of mushroom. A numerical tool for analysing data from gamma spectroscopy has been constructed. Two different methods for calculating counts in energy peaks from gamma emission spectra have been made and have been the basis for the further work. During this work the following has been determined: The efficiency of a high purity germanium (HPGe) detector, the activity of two different mushroom samples, the attenuation coefficient of gamma at 662 keV for these samples and for water. In order to be able to approximate a can filled with mushroom as an isotropic radiating point source and get accurate results, the activity measurements need to be carried out with a great distance between the sample and the detector. A consequence of this is that this approximation is only suitable for high-activity mushroom, which became evident when the activity of a low-activity mushroom could not be decided with decent statistics even though single measurements were carried out in almost a weeks time. Systematic errors are not considered during this work, only statistical uncertainties.

A majority of research within the field of energetic materials have been centered around the stable crystalline phase, whilst there has been less about the amorphous phase and the implications of these types of material. In this study, Molecular Dynamics simulations with the General Amber Force Field (GAFF) is used to predict fundamental properties of the nitramine explosives HMX and CL-20 in the amorphous phase. Amorphous structures are obtained by compressing a molecular gas to 4 GPa followed by relaxation and equilibration. The simulations indicate that the amorphous phases of HMX and CL-20 have lower densities than the corresponding crystal phases, 12.7% and 7.3% respectively. Both HMX and CL-20 was found to compress more easily when subject to external pressure, the difference was most significant for HMX.As a second part of this study an amorphous composition of CL-20/HMX/Polyvinylacetate(PVAc) (50/45/5 -wt%) was studied. This was obtained by compressing a molecular gas to varying pressures followed by relaxation and equilibration. Results indicate that the simulated density around 1.64 [g/cm3 ] fall close to experimental observations of 1.7 [g/cm3 ]. The density was observed to not vary significantly for pressures higher than 0.4 [GP a] in accordance to experimental data.

Ruthenium complexes has been geometrically optimized with different combinations of basis sets. Using single point calculation, the Density of States and partial Density of States has been calculated. RuIII-OH2 experienced a shift towards higher binding energies. The Ru atom plays a vast role in the contribution to the HOMO level of each complex, dominating in RuII-OH2. The nitrogen atom gives a small contribution for each complex in the HOMO region except for RuII-OH2 where it only appears at higher binding energies. The energy difference between RuII-OH2 and RuIII-OH/RuIV-O is about 1.1 eV whereas it experimentally is shown to be around 1.5 eV for the same complexes.