Optical frequency comb spectroscopy (OFCS) combines two previously exclusive features, i.e., wide optical bandwidth and high spectral resolution, enabling precise measurements of entire molecular bands and simultaneous monitoring of multiple gas species in a short measurement time. Moreover, the equidistant mode structure of frequency combs enables efficient coupling of the comb power to enhancement resonant cavities, yielding high detection sensitivities. Different broadband detection methods have been developed to exploit the full potential of frequency combs in spectroscopy, based either on Fourier transform spectroscopy or on dispersive elements.There have been two main aims of the research presented in this thesis. The first has been to improve the performance of mechanical Fourier transform spectrometers (FTS) based on frequency combs in terms of sensitivity, resolution and spectral coverage. In pursuit of this aim, we have developed a new spectroscopic technique, so-called noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS), and achieved a shot-noise-limited sensitivity and low ppb (parts-per-billion, 10−9) CO2 concentration detection limit in the near-infrared range using commercially available components. We have also realized a novel method for acquisition and analysis of comb-based FTS spectra, a so-called sub-nominal resolution method, which provides ultra-high spectral resolution and frequency accuracy (both in kHz range, limited only by the stability of the comb) over the broadband spectral range of the frequency comb. Finally, we have developed an optical parametric oscillator generating a frequency comb in the mid-infrared range, where the strongest ro-vibrational molecular absorption lines reside. Using this mid-infrared comb and an FTS, we have demonstrated, for the first time, comb spectroscopy above 5 μm, measured broadband spectra of several species and reached low ppb detection limits for CH4, NO and CO in 1 s.The second aim has been more application-oriented, focused on frequency comb spectroscopy in combustion environments and under atmospheric conditions for fast and sensitive multispecies detection. We have demonstrated, for the first time, cavity-enhanced optical frequency comb spectroscopy in a flame, detected broadband high temperature H2O and OH spectra using the FTS in the near-infrared range and showed the potential of the technique for flame thermometry. For applications demanding a short measurement time and high sensitivity under atmospheric pressure conditions, we have implemented continuous-filtering Vernier spectroscopy, a dispersion-based spectroscopic technique, for the first time in the mid-infrared range. The spectrometer was sensitive, fast, robust, and capable of multispecies detection with 2 ppb detection limit for CH4 in 25 ms. / Optisk frekvenskamspektroskopi (OFCS) kombinerar två tidigare icke förenliga egenskaper, dvs. ett brett optiskt frekvensområde med en hög spektral upplösning, vilket möjliggör noggranna mätningar av hela molekylära absorptionsband och detektion av flera gaser samtidigt med en kort mättid. Eftersom frekvenskammar har en regelbunden struktur med jämnt separerade laser moder kan man effektivt koppla kammen till en optisk kavitet och därmed möjliggöra frekvenskamsdetektion med hög känslighet. Olika metoder har utvecklats för att utnyttja frekvenskammarnas fulla potential för spektroskopi, baserad på antingen Fouriertransform-spektroskopi eller dispersiva element.Forskningen som presenteras i denna avhandling har haft två huvudmål. Det första har varit att förbättra prestandan hos mekaniska Fourier-transformspektrometrar (FTS) baserat på frekvenskammar med avseende på känslighet, upplösning och spektral täckning. I strävan efter detta har vi utvecklat en ny spektroskopisk teknik, benämnd brusimmun kavitetsförstärkt optisk frekvenskamspektroskopi (NICE-OFCS), och uppnått en hagelbrusbegränsad känslighet och detektionsgränser ner till låga ppb koncentrationer (miljarddelar, 10−9) för CO2 i det när-infraröda frekvensområdet enbart med användning av kommersiellt tillgängliga komponenter. Vi har också utvecklat en ny metod för insamling och analys av kambaserade FTS-spektra, som betecknas ha sub-nominell upplösning. Metoden gör det möjligt att uppnå ultrahög spektral upplösning och hög frekvensnoggrannhet (båda i kHz-området, endast begränsad av kammens stabilitet) över kammens hela frekvensområde. Slutligen har vi utvecklat en optisk parametrisk oscillator som genererar en frekvenskam i det mid-infraröda frekvensområdet, där de starkaste rotations-vibrationsmolekylära absorptionslinjerna finns. Med hjälp av denna kam och en FTS har vi för första gången demonstrerat frekvenskamspektroskopi över 5 μm. Vi har detekterat bredbandsspektra av flera molekylära gaser och har, för mättider på 1 s, uppnått detektionsgränser ner till låga ppb halter för CH4, NO och CO.Det andra syftet har varit mer applikationsorienterat: att använda frekvenskamspektroskopi i förbränningsmiljö och under atmosfäriska förhållanden för snabb och känslig multiämnesdetektion. Vi har för första gången demonstrerat kavitetsförstärkt optisk frekvenskamspektroskopi i en flamma, där vi har detekterat högtemperaturspektra av H2O och OH i det när-infraröda området med användning av FTS och visat teknikens potential för termometrisk karakterisering av flammor. För applikationer som kräver en kort mättid och hög känslighet under atmosfäriska förhållanden har vi utvecklat ett detektionssystem baserat på Vernier-spektroskopi med kontinuerlig filtrering, vilket är en dispersionsbaserad teknik, för första gången i det mid-infraröda frekvensområdet. Det befanns att spektrometern var känslig, snabb, robust och kapabel till multiämnesdetektion med en detektionsgräns på 2 ppb för CH4 för korta mättider (25 ms).

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[pt] O ferro é extraído sob a forma de minério de ferro, sendo 99 por cento utilizado na indústria siderúrgica. Os documentos normativos existentes indicam a volumetria como à técnica analítica para quantificar o teor de ferro em minério de ferro, com exceção da ISO 9516-1: 2003, que, recomenda a espectrometria de fluorescência de raios-X por comprimento de onda (WDXRF). Na literatura são descritos estudos utilizando a espectrometria de fluorescência de raios-X por dispersão de energia (EDXRF) para quantificar ferro em minério de ferro, mas em nenhuma destas publicações é caracterizada a confiabilidade metrológica e a incerteza de medição, sendo outros aspectos importantes na seleção de um método analítico o impacto económico e tempo de análise. No presente trabalho realizou-se um estudo comparativo de impacto económico, tempo de análise e desempenho metrológico na quantificação de ferro em minério de ferro por meio da técnica de EDXRF, comparando-o com a espectrofotometria de absorção molecular e volumetria (titulação com dicromato de potássio), abrangendo a incerteza de medição e a avaliação de parâmetros de validação para EDXRF. A análise volumétrica foi realizado baseado nas normas ANBT NBR 8577:2011 e ASTM E246:2010. Na espectrofotometria de absorção molecular, adaptou-se o método da ortofenantrolina descrito na norma ABNT NBR 13934:1997. Nas outras técnicas precisam-se da abertura da amostra, na EDXRF, as amostras foram preparadas na forma de pastilha (pó de minério prensado). Os métodos avaliados apresentaram desempenhos metrológicos equivalentes, os melhores indicadores de custo e tempo em longo prazo foram observados para o método por EDXRF na quantificação do teor de ferro em minério. / [en] After its extraction in the form of iron ore, 99 per cent of the iron is employed in the steel industry. The normative documents existents recommend to volumetry as the technical analytic for quantification of iron in iron ore, with the exception of ISO 9516-1: 2003, which recommends the fluorescence spectrometry X-ray wavelength (WDXRF). In literature, there are studies using energy dispersive Xray fluorescence spectrometry (EDXRF) to quantify iron in iron ore, but none of these is characterized by complete validation and measurement uncertainty. Other aspects to be considered when selecting an analytical method are the financial cost and the time for analysis. In this work it is carried out a comparative study of financial cost, time analysis and metrological performance on quantification of iron ore through the EDXRF technique, in comparison with the results obtained by molecular absorption spectrophotometry and volumetry (titration with potassium dichromate), including measurement uncertainty evaluation and some parameter of validation for EDXRF. The molecular absorption spectrophotometry measurements were performed by colorimetric orthophenanthroline method. Unlike the other approaches that require sample preparation with acid, for EDXRF measurements, samples were prepared in tablet form (pressed iron ore powder). The evaluated methods presented equivalent metrological performances on determining iron in ore, but the best long-term outcome for cost was observed in the results obtained by EDXRF method.

Um procedimento baseado no uso sequencial de simulação Monte Carlo e cálculos de Mecânica Quântica é proposto e usado para o tratamento de efeitos de solvente, com especial atenção parao sovatocromismo no espectro de absorção molecular. A ideia básica é realizar simulações clássicas com o método Monte Carlo para gerar estruturas supermoleculares do sistema em solução e em seguida tratar estas supermoléculas (soluto, solvente e suas interações) com cálculos quânticos. Um modelo totalmente discreto do solvente é utilizado e, portanto, o uso de meios dielétricos contínuos é dispensado. Neste procedimento, as supermoléculas são compostas por uma molécula do soluto rodeada pela primeira camada de solvatação definida através da função distribuição. Os efeitos de solvente são calculados usando médias configuracionais sobre estruturas supermoleculares descorrelacionadas obtidas através de análises estatísticas das simulações. Como aplicação, os deslocamentos espectrais da primeira banda de absorção do benzeno 1B2u(- *), devido a presença de diversos solventes, foram analisados e calculados. Boa concordância com os resultados experimentais foram obtidos. / A approach based on the sequential use of Monte Carlo simulation and Quantum Mechanics is proposed and use for the treatment of solvent effects with special attention to solvatochromic shifts. The basic Idea is to perform a classical Monte Carlo simulation to generate supermolecular structures of the system, then to treat these supermolecules (solute, solvent and all its interaction) by quantum mechanics. This is a totally discrete modelo f the solvent that avoids the use of a dielectric continuum. In this approach, the supermolecules are composed by the solute molecule surrounded by the first solvation Shell as determined by the distribution function. The solvent effects are calculated using ensemble average over uncorrelated supermolecular structures obtained by statistical analysis. As na application, the spectral shifts of the 1B2u(- *) trnsition of benzene in different solvents are investigated. Good agreement with the experimental results are obtained.

Um procedimento baseado no uso sequencial de simulação Monte Carlo e cálculos de Mecânica Quântica é proposto e usado para o tratamento de efeitos de solvente, com especial atenção parao sovatocromismo no espectro de absorção molecular. A ideia básica é realizar simulações clássicas com o método Monte Carlo para gerar estruturas supermoleculares do sistema em solução e em seguida tratar estas supermoléculas (soluto, solvente e suas interações) com cálculos quânticos. Um modelo totalmente discreto do solvente é utilizado e, portanto, o uso de meios dielétricos contínuos é dispensado. Neste procedimento, as supermoléculas são compostas por uma molécula do soluto rodeada pela primeira camada de solvatação definida através da função distribuição. Os efeitos de solvente são calculados usando médias configuracionais sobre estruturas supermoleculares descorrelacionadas obtidas através de análises estatísticas das simulações. Como aplicação, os deslocamentos espectrais da primeira banda de absorção do benzeno 1B2u(- *), devido a presença de diversos solventes, foram analisados e calculados. Boa concordância com os resultados experimentais foram obtidos. / A approach based on the sequential use of Monte Carlo simulation and Quantum Mechanics is proposed and use for the treatment of solvent effects with special attention to solvatochromic shifts. The basic Idea is to perform a classical Monte Carlo simulation to generate supermolecular structures of the system, then to treat these supermolecules (solute, solvent and all its interaction) by quantum mechanics. This is a totally discrete modelo f the solvent that avoids the use of a dielectric continuum. In this approach, the supermolecules are composed by the solute molecule surrounded by the first solvation Shell as determined by the distribution function. The solvent effects are calculated using ensemble average over uncorrelated supermolecular structures obtained by statistical analysis. As na application, the spectral shifts of the 1B2u(- *) trnsition of benzene in different solvents are investigated. Good agreement with the experimental results are obtained.

The thesis analyzes the optical laser range finders in real propagation environments. Itdescribes the various parts of optical laser range finders their properties and principles in relation to their performance balance. The paper presents the basic optical properties of lenses used in the transmitter and receiver. A separate chapter is devoted to the transit time method and factors influencing the measurement. The proportional directional reflectance analysisis a part of the thesis. In conclusion, the thesis contains the practical laboratory measurements of the relative directional reflectance of different materials and colors, and verification of the power level diagram.

Im ersten Teil wurde Probenvorbereitungs-Methoden und instrumentelle Methoden zur Organofluor-Bestimmung verglichen, um Vor- und Nachteile bei der Summenparameter-Analytik von per- und polyfluorierten Alkylverbindungen (PFAS) zu identifizieren. Daher wurden Oberflächenwasserproben aus der Spree in Berlin und Industrieabwasserproben mit zwei PFAS-Summenparametern analysiert – dem extrahierbaren (EOF) und dem adsorbierbaren organisch gebundenen Fluor (AOF). Beide PFAS-Summenparameter wurden mit zwei fluorsensitiven Detektionssystemen analysiert – Hochauflösender Kontinuumstrahler-Graphitofen Molekülabsorptionsspektrometrie (HR-CS-GFMAS) und combustion Ionenchromatographie (CIC). HR-CS-GFMAS erwies sich im Vergleich zu CIC als der empfindlichere und schnellere Ansatz mit höherer Präzision. Im zweiten Teil wurde eine neue Methode zur PFAS-Summenparameteranalyse und EOF-Bestimmung in Bodenproben auf Basis von HR-CS-GFMAS entwickelt und optimiert. EOF-Massenanteile wurden bei mehrfacher Extraktion und Nutzung der Festphasenextraktion (SPE) zur Entfernung anorganischen Fluors untersucht. Bei einem Vergleich der optimierten Methode mit und ohne SPE zeigte sich eine drastische Diskriminierung von Organofluor-Verbindungen mittels SPE. Im dritten Teil wurden Organofluor-Massenbilanzen in aquatischen Systemen anhand von Oberflächenwasser- und Schwebstoffproben (SPM) untersucht. SPM-Proben wurden mit vier komplementären Analysemethoden analysiert – target und non-target, direct total oxidizable precursor assay (dTOPA) und EOF. Daher wurden drei Organofluor-Massenbilanzansätze für die räumlich und zeitaufgelöste SPM-Probenanalyse verwendet: (I) Identifizierung von oxidierbaren PFAS-Vorläufer, (II) Identifizierung des Anteils der identifizierten und nicht identifiziertes EOF und (III) PFAS-target, PFAS dTOPA, non-target-Screening und EOF-Analyse, um das nicht identifizierte EOF aus Ansatz (II) weiter zu entschlüsseln. / In the first part, a comparison of sample preparation and instrumental methods for organofluorine determination was used to identify advantages and disadvantages in sum parameter analysis of per- and polyfluoroalkyl substances (PFASs). Therefore, surface water samples from the Spree River in Berlin, Germany and industrial effluent samples were analyzed using two PFAS sum parameters – the extractable (EOF) and adsorbable organically bound fluorine (AOF). Both PFAS sum parameters were analyzed using two fluorine sensitive detection systems – high-resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) and combustion ion chromatography (CIC). HR-CS-GFMAS turned out to be the more sensitive and faster approach accompanied with higher precision compared to CIC. In the second part, a new method for PFAS sum parameter analysis and EOF determination in soil samples based on HR-CS-GFMAS was developed and optimized. EOF mass fractions were investigated upon multiple extraction and utilization of solid phase extraction (SPE) for inorganic fluorine removal. In a comparison of the optimized method with and without SPE, a highly biased discrimination of organofluorines using SPE was shown. In the third part, organofluorine mass balances were investigated in aquatic systems using surface water and suspended particulate matter (SPM) samples. SPM samples were analyzed using 4 complementary analytical methods – target and non-target HRMS, direct total oxidizable precursor assay (dTOPA) and EOF. Therefore, 3 organofluorine mass balance approaches were used for SPM sample analysis in spatial and time resolved manner: (I) Identification of oxidizable PFAS precursors, (II) Identification of the proportion of identified and unidentified EOF and (III) PFAS target, PFAS dTOPA, non-target screening and EOF analysis to further unravel the unidentified EOF from approach (II).