Moderne optoelektronische Dünnfilmapplikationen erfordern den Einsatz effizienter großflächiger Elektrodensysteme, die einerseits über sehr gute Leitfähigkeitseigenschaften verfügen und andererseits eine hohe Transparenz in einem breiten Wellenlängenspektrum aufweisen. Momentan wird für derartige Anwendungen zum Großteil der Werkstoff Indiumzinnoxid (ITO) eingesetzt, dessen Hauptbestandteil Indium nur in geringen Mengen auf der Erde vorkommt. Für die Erhaltung der Marktfähigkeit und zur Weiterentwicklung der Dünnschichtelektronik ist es nötig, dieses Ressourcenproblem zu lösen. Eine Möglichkeit zur Substitution von ITO ist die Verwendung dünner metallischer Filme als transparente Elektroden. Die vorliegende Dissertationsschrift untersucht in diesem Zusammenhang die Anwendung der Direkten Laserinterferenzstrukturierung (DLIP). Um hinreichend große optische Transparenz bei entsprechender elektrischer Leitfähigkeit zu erhalten, werden Dünnschichtensysteme aus Kupfer, Aluminium, Chrom und Silber mit verschiedenen periodischen Lochmustern zwischen 1,5-2,7 µm perforiert. Im Anschluss werden die bearbeiteten Probenkörper hinsichtlich ihrer optischen, elektrischen und topografischen Eigenschaften vermessen. Die umfangreichen gewonnenen Daten werden in einer Auswertung zusammengefasst und mit Resultaten aus numerischen Modellrechnungen verglichen. Neben den Ergebnissen zur Effizienzsteigerung der Dünnfilme untersucht die vorliegende Arbeit die laserinduzierte Ablationsdynamik metallischer Filme auf Glassubstrat zwischen 5-40 nm Schichtdicke.:1 Einleitung 1 2 Theoretische Grundlagen 4 2.1 Verfahren zur Herstellung von Dünnschicht-Elektroden 4 2.1.1 Verdampfungsverfahren 4 2.1.2 Sputterverfahren 5 2.1.3 Metallorganische Gasphasenepitaxie – MOCVD 6 2.2 Schichtwachstum von Metallfilmen in PVD-Verfahren 7 2.3 Elektrische Eigenschaften von Dünnschicht-Elektroden 9 2.3.1 Mechanismen der elektrischen Leitung in Festkörpern 9 2.3.2 Elektrische Charakteristika von Indiumzinnoxid-Schichten 10 2.3.3 Elektrische Charakteristika dünner Metallschichten 10 2.4 Optische Eigenschaften dünner Schichten 13 2.4.1 Wechselwirkung von Licht mit Materie 13 2.4.2 Lichtmanipulation durch periodische Strukturen 14 2.4.3 Optische Eigenschaften transparenter ITO-Schichten 17 2.4.4 Optische Eigenschaften metallischer Dünnschichten 18 2.5 Grundlagen lasergestützter Bearbeitungsmethoden 19 2.5.1 Materialablation durch gepulste Laserstrahlung 19 2.5.2 Theoretische Grundlagen zur Bestimmung der Ablationsschwelle 21 2.6 Verfahren zur Mikrostrukturierung von Oberflächen 22 2.6.1 Elektronenstrahl-Lithographie 23 2.6.2 Sequentielles Laserstrukturieren 24 2.6.3 Strukturieren mit Laserinterferenz 25 2.7 Aktueller Forschungsstand zur DLIP dünner Metallschichten 29 2.7.1 DLIP metallischer Filme mit Nanosekunden-Pulsen 29 2.7.2 DLIP metallischer Filme mit Pikosekunden-Pulsen 35 3 Experimentelle Arbeit 37 3.1 Entwicklung numerischer Rechenmodelle 37 3.1.1 Modellierung des Interferenzvolumens 37 3.2 Thermische Simulationen 38 3.3 Experimente und Versuchsanordnungen 42 3.3.1 Verwendete Lasersysteme 42 3.3.2 Vorgehensweise zur Bestimmung der Ablationsschwellwerte 42 3.3.3 Laser-Annealing metallischer Dünnschichten 43 3.3.4 Direkte Laserinterferenzstrukturierung 44 3.3.5 Übersicht der verwendeten Dünnfilmsubstrate 47 3.3.6 Mess- und Analysemethoden 49 4 Auswertung und Diskussion 55 4.1 Ermittlung der Ablationsschwellwerte 55 4.1.1 Ablationsschwellwerte bei Nanosekunden-Pulsen 55 4.1.2 Ablationsschwellwerte bei Pikosekunden-Pulsen 58 4.2 Charakterisierung unbehandelter Dünnschichten 58 4.2.1 Topographische Eigenschaften unbehandelter Metalldünnschichten 58 4.2.2 Optische und Elektrische Eigenschaften unbehandelter metallischer Filme 59 4.3 Charakterisierung lasergeglühter Metalldünnschichten 60 4.3.1 Optische Eigenschaften lasergeglühter Metallfilme 60 4.3.2 Elektrische Eigenschaften lasergeglühter Metallschichten 61 4.3.3 Schlussfolgerungen aus den Annealing-Experimenten 63 4.4 Ergebnisse der Modellrechnungen 63 4.4.1 Mathematische Simulation der Interferenzeigenschaften 63 4.5 Charakterisierung DLIP-strukturierter Metalldünnschichten 67 4.5.1 DLIP-Strukturierung von Silberdünnschichten ns-Pulsen 67 4.5.2 DLIP-Strukturierung von Silberdünnschichten mit ps-Pulsen 71 4.5.3 DLIP-Strukturierung von Kupferdünnschichten mit ns-Pulsen 77 4.5.4 DLIP-Strukturierung von Kupferdünnschichten mit ps-Pulsen 89 4.5.5 DLIP-Strukturierung von Aluminiumdünnschichten mit ns-Pulsen 93 4.5.6 DLIP-Strukturierung von Aluminiumdünnschichten mit ps-Pulsen 106 4.5.7 DLIP-Strukturierung von Chromdünnschichten mit ns-Pulsen 111 4.5.8 Charakterisierung DLIP-strukturierter Vielschicht-Substrate 116 4.6 Optische Charakterisierung 118 4.6.1 Optische Eigenschaften mittels ns-Pulsen strukturierter Filme 119 4.6.2 Optische Eigenschaften mittels ps-Pulsen strukturierter Filme 127 4.6.3 Optische Charakterisierung DLIP-strukturierter Vielschicht-Substrate 129 4.7 Elektrische Eigenschaften 131 4.7.1 Schichtwiderstand DLIP-strukturierter Metallelektroden 131 4.7.2 Schichtwiderstand DLIP-strukturierter Vielschicht-Elektroden 140 5 Zusammenfassung 144 6 Ausblick 149 7 Literaturverzeichnis 150 8 Anhang 161

Die ASFiNAG unterhält mehr als 5.000 Brückenobjekte im Straßennetz. Die meisten von ihnen wurden in Stahlbeton- oder Spannbetonbauweise errichtet und insbesondere die Stützen sind hohen Belastungen durch Chlorid ausgesetzt. Dies führt langfristig zu einer Verringerung der Dauerhaftigkeit und Instandsetzungen sind daher erforderlich. Eine genaue Ermittlung der Depassivierung und ein Prognosemodell sind bei Chloridbelastung besonders wichtig für eine kosteneffiziente Erhaltung. Die neue Methode LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) ermöglicht exaktere Ergebnisse als die traditionelle Chloridbestimmung mittels Titration. Die Vorteile der beiden Methoden werden im Beitrag diskutiert und die Ergebnisse verglichen. Es wird gezeigt, dass die LA-ICP-MS-Methode zuverlässigere Ergebnisse liefert und durch die hohe Ortsauflösung der Chloridprofile sowie die genaue Bestimmung des Chloridgehalts noch nicht dagewesene Möglichkeiten für eine exakte Beurteilung und Prognose eröffnet.

Os nefelina sienitos miasquíticos a intermediários do Maciço Alcalino Poços de Caldas (MAPC), em especial o tipo da Pedreira, possuem enclaves microgranulares félsicos e máficoultramáficos intrigantes. O nefelina sienito da Pedreira (NeS) pode ser divido em duas fácies texturais: uma de granulação média-grossa a grossa (NeS-g), outra de granulação média-fina a fina (NeS-f). O NeSg possui, mais comumente, enclaves microgranulares félsicos (EMF), de composição fonolítica. Estes enclaves podem envolver enclaves menores, máfico-ultramáficos, gerando enclaves duplos. O NeSf apresenta mais tipicamente enclaves microgranulares máfico-ultramáficos (EMM), ora com feições de rompimento em estado plástico, ora com bordas angulosas e lineares. Diques de composição fonolítica cortam o NeS-g. As rochas estudadas neste trabalho são constituídas por nefelina, feldspato alcalino e clinopiroxênio. Como fase acessória, têm-se titanita, magnetita e biotita-flogopita. Apatita ocorre também como mineral acessório, com exceção para o NeS-g. No NeS-g, no NeS-f e nos EMF, o clinopiroxênio possui duas fases texturais: uma prismática, verde (egirina-augita) que também pode ter núcleo róseo/incolor (diopsídio, mais comum no NeS-f e no EMF); outra fibrosa, também verde, porém fortemente pleocroica (egirina). Os EMM são constituídos essencialmente por diopsídio, com M(médio)~80. Quando porfirítico, o enclave possui macrocristais de diopsídio róseo/incolor (#mg~0,9) imersos numa matriz de diopsídio verde (#mg~0,8), ambos prismáticos. Magnetita dos NeS possui pouca variação, com teores baixos de Ti, diferente da magnetita dos enclaves. A assinatura química da nefelina dos EMM é equivalente à do NeS-f, com mais Fe3+ e menos K em relação ao NeS-g. Feldspato alcalino tende a ser mais potássico nos EMF e apresenta maior variação composicional nos EMM (Ab10-33Or72-80). Biotita está presente somente nos EMF e flogopita somente nos EMM. O padrão de elementos terras raras (ETR) do clinopiroxênio róseo/incolor do NeS-f é semelhante ao do EMM. Egirina-augita e egirina possuem enriquecimento em ETR pesados. Os enclaves máfico-ultramáficos são ultrabásicos, classificados como tefritos/basanitos (Le Bas et al., 1986) ou nefelinitos/ankaratritos (De La Roche et al., 1980), enquanto as rochas félsicas são intermediárias, correspondentes a fonolitos ou nefelina sienitos, dependendo da granulometria. Os diques e o NeS-f são peralcalinos, enquanto o EMF, o NeS-g e os EMM são peralcalinos/metaluminosos. As rochas ultramáficas/ultrabásicas, aflorantes na porção noroeste do Maciço Alcalino Poços de Caldas (Ulbrich et al., 2002), possuem padrões de ETR que indicam que estas rochas podem estar geneticamente ligadas aos enclaves máfico-ultramáficos. De uma forma geral, as características estruturais, texturais e químicas das rochas estudadas corroboram com a hipótese de coexistência de pelo menos dois magmas distintos: um félsico sienítico insaturado outro ultramáfico/ultrabásico, que teriam interagido e formado os os EMM e o NeSf, principalmente. Enquanto num estágio posterior de cristalização do magma, porém ainda em estado plástico, o dique teria se colocado, com parcial absorção da rocha pelos nefelina sienitos, formando os EMF. / The miaskitic to intermediate nepheline syenites of Poços de Caldas Alkaline Massif, especially the Pedreira type, have intriguing felsic and mafic-ultramafic microgranular enclaves. The Pedreiras nepheline syenite type (NeS) can be divided into two textural facies: one that is medium-coarse to coarse grained (NeS-c) and the other that varies between medium-fine to fine grained (NeS-f). It is common among the NeS-c microgranular felsic enclaves (MFE) with phonolitic composition. These enclaves may develop smaller ones maficultramafic, generating double enclaves. The NeS-f usually presents mafic-ultramafic enclaves (MME), sometimes showing disrupted features in plastic stage and sometimes angular and linear edges. Phonolitic dykes cut the NeS-c. The rocks studied in this work are formed by nepheline, alkali-feldspar and clinopyroxene. The accessory phase is characterized by titanite, magnetite and biotite-phlogopite. In exception to the NeS-c, apatite also occurs as an accessory mineral. In the NeS-c, NeS-f and MFE, the clinopyroxene presents two textural phases: a green prismatic one (aegirine-augite), which also may have a pinkish/colourless core (diopsyde, which is common in the NeS-f and MFE); the other one is fibrous, also green, however with strongly pleocroism (aegirine). Essencially, the MME are formed by diopsyde, with M(medium)~80. When porphyritic, the enclave has macrocrystals of pinkish/colourless diopsyde (with mg#~0,9) in a green diopsyde (mg#~0,8) matrix, both prismatic. In the NeS, the magnetite varies little: with low levels of Ti, differently from the enclaves magnetite. The chemical signature of the nepheline in the MME equals to the one present in the NeS-f and has more Fe3+ and less K when compared to the NeS-c. The alkaline feldspar in the MFE has more potassium in its structure and presents a higher compositional variation in the MME (Ab10-33Or72-80). It is also noticeable that biotite is a component only to the MFE, while the phlogopite occurs in the MME. The rare earth elements (REE) pattern in the pinkish/colourless clinopyroxene of the NeS-f is similar to the MME. Both aegirine-augite and aegirine present an enrichment regarding the heavy REE. The MME are ultrabasic, classified as tephrite/basanite (Le Bas et al., 1986) or nephelinite/ankaratrites (De La Roche et al., 1980), while the felsic rocks are intermediate, corresponding to phonolite and nepheline syenite, depending on the grain size. The dykes and the NeS-f are peralkaline, while the MFE, NeS-c and the MME are peralkaline/metaluminous. The ultrabasic/ultrapotassic rocks, outcropping in the northwestern portion of the PCAM (Ulbrich et al., 2002), have REE patterns wich indicate that these rocks may be genetically related to mafic-ultramafic enclaves. Generally, the structural, textural and chemical signatures of the rocks studied in this work confirm the hypothesis of the coexistence of at least two different magmas: a syenitic undersaturated felsic one and a ultramafic/ultrabasic one, and their interaction resulted in the MME and, above all, the NeS-f. While in a late stage of magma cristalization, but still in the plastic state, the dike would be placed, with partial absorption of the rock by the nepheline syenite, resulting in the EMF.

Sandby borg, an Iron Age ringfort on Öland, Sweden has been and is still at the center of attention in media and archaeological research. The massacre uncovered at the site during recent years opens many doors for analyses on the Migration Period (c. 400-550 AD) Iron Age skeletal remains. Eighteen teeth (molars) from 12 individuals and three rodent teeth were chosen for strontium (87Sr/86Sr) analyses. This was done to establish whether these individuals were locals or non-locals to Öland. The analyses displayed a, for the most part, local 87Sr/86Sr ratio. Two non-locals were identified, as well as a pattern of higher 87Sr/86Sr peaks on numerous of the individuals during a certain age span, which could indicate a local weaning process with a special food. / Sandby borg

<p>Due to the small dimensions, nanoparticles and materials consisting of nano-sized building blocks exhibit unique — mostly superior — properties, well differing from their bulk counterpart. Most of the novel properties of nanoparticles (and nanomaterials) are size-dependent, while the majority of the common gasphase methods used for generation of nanopowders result in different, usually wide, size-dispersions. Further understanding of the fundamental processes leading to particle formation is therefore required, leading to better control of size and distribution of the nanoparticles, thus allowing engineering of the desired properties for both nanoparticles and nanomaterials.</p><p>In this present thesis, nanoparticles were produced by two different gasphase techniques activated by lasers, namely laser chemical vapor deposition (LCVD) and pulsed laser ablation (PLA). Optical emission spectroscopy (OES) was performed on thermal (blackbody-like) radiation originating from laser-excited particles during LCVD and coupled to measured size-distributions. In-situ monitoring of size-distributions by a differential mobility analyzer (DMA) was employed during PLA. In addition, deposited nanoparticles were characterized by a variety of standard techniques.</p><p>Different cooling mechanisms of the laser-excited gasphase particles were identified based on temperature and emitted intensity data extracted from OES measurements. The strong evaporation at elevated temperatures also allowed direct size manipulation of the particles. By monitoring the intensity of the emitted thermal radiation and the scattered laser line, strong indications about the so called coagulation limit, where a broadening of the size-distribution occurred, was obtained. The DMA monitoring, supported by modeling, gave information about different mechanisms (thermal and photochemical) of the ablation process, and particle condensation well below the ablation threshold was also found.</p>

Graduation date: 2002

Due to the small dimensions, nanoparticles and materials consisting of nano-sized building blocks exhibit unique — mostly superior — properties, well differing from their bulk counterpart. Most of the novel properties of nanoparticles (and nanomaterials) are size-dependent, while the majority of the common gasphase methods used for generation of nanopowders result in different, usually wide, size-dispersions. Further understanding of the fundamental processes leading to particle formation is therefore required, leading to better control of size and distribution of the nanoparticles, thus allowing engineering of the desired properties for both nanoparticles and nanomaterials. In this present thesis, nanoparticles were produced by two different gasphase techniques activated by lasers, namely laser chemical vapor deposition (LCVD) and pulsed laser ablation (PLA). Optical emission spectroscopy (OES) was performed on thermal (blackbody-like) radiation originating from laser-excited particles during LCVD and coupled to measured size-distributions. In-situ monitoring of size-distributions by a differential mobility analyzer (DMA) was employed during PLA. In addition, deposited nanoparticles were characterized by a variety of standard techniques. Different cooling mechanisms of the laser-excited gasphase particles were identified based on temperature and emitted intensity data extracted from OES measurements. The strong evaporation at elevated temperatures also allowed direct size manipulation of the particles. By monitoring the intensity of the emitted thermal radiation and the scattered laser line, strong indications about the so called coagulation limit, where a broadening of the size-distribution occurred, was obtained. The DMA monitoring, supported by modeling, gave information about different mechanisms (thermal and photochemical) of the ablation process, and particle condensation well below the ablation threshold was also found.

This research deals with the synthesis and characterization (transmission electron microscopy and optical spectroscopy) of composite nanocondensates produced by pulse laser ablation (PLA) on Zn, Zn-Cu and Cu-Au targets in liquid or vacuum. First, wurtzite-type (W)-ZnO and

Amorphous metals have been discovered in 1960 and, because of their structures, exhibit very unique mechanical, magnetic and chemical properties that can have various applications. These properties qualify them as the potential material of the future. This work focuses on a new laser ablation technique to synthesize nanoparticles of amorphous metals from aqueous feedstock. One of the critical factors in the production of amorphous metal is the cooling rate used to synthesize them. The laser ablation of microparticle aerosol (LAMA) process used in this work, with a cooling rate estimated of 10¹² K/s, has all the characteristics required for the production of such metallic glasses. A Collison nebulizer is used to generate microdroplets of a nitrate solution containing the corresponding ratio of metals for the production of a Zr-Al-Ni based alloy. Once dried and conditioned, these microdroplets leave solid microparticles which are ablated by an excimer laser producing nanoparticles that are then filtered by virtual impaction. In order to characterize the nanoparticles obtained with this process nanoparticulate films produced by LAMA have been analyzed by optical profilometry, scanning electron microscopy (SEM) equipped with energy-dispersive x-ray spectroscopy (EDS) and transmission electron microscopy (TEM) equipped with EDS. The results agree with a hypothesis that the films contain oxidized, amorphous metal on the surface of the films. When the films are thin, they are fully oxidized, and simultaneous segregation of Zr occurs to the surface. The hypothesis and the results are discussed. / text

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