Single micro particle wide range sizing and speed by light scattering

Tese de mestrado integrado em Engenharia física, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2014O ar que nos rodeia, embora invisível ao olho humano, contém uma grande quantidade de partículas de diferentes tipos e propriedades físicas. Estas partículas transportadas pelo ar, ou aerossóis, afectam-nos todos os dias em todos os aspectos como na saúde, no ambiente e até na economia fazendo com que o estudo destes aerossóis seja uma área importante de investigação. Para medir as propriedades destas partículas, diferentes tecnologias já o permitem e estão disponíveis comercialmente. No entanto, existem dois factores que limitam estas tecnologias: resolução e o momento em que os dados são processados. Normalmente apenas um é escolhido, deixando o outro de lado, ou seja, quando há resolução, é necessário muito tempo até se obter resultados e, contrariamente, quando há detecções em tempo real, perde-se resolução. O sistema descrito nesta tese pertence à parte inicial de um dispositivo que irá preencher essa lacuna, permitindo resolução em tempo real. Neste documento, será apresentado um pequeno capítulo teórico, onde será dada especial importância ao efeito da dispersão da luz e serão descritos alguns métodos matemáticos que foram usados para obter os resultados; o segundo capítulo será focado no detector, onde todos os componentes serão descritos em detalhe; o terceiro capítulo irá apresentar os resultados; no quarto capítulo serão expostas três aplicações que utilizaram este sistema para obter dados reais durante o meu estágio; e o capítulo final irá apresentar as conclusões e perspectivas futuras para este projecto. Quando cheguei, um dos sistemas já estrava na sua fase final de construção e o meu papel neste projecto iniciou-se exactamente aqui, começando por desenvolver técnicas de alinhamento e teste, optimização e pequenas melhorias, programação e análise de dados e finalmente teste e reparação de todo o sistema em diferentes ambientes. No final deste estágio, este sistema conseguiu detectar e discriminar partículas de tamanho diferente.The air that surrounds us, while invisible to the human eye, contains a huge quantity of particles of different kind and physical properties. These airborne particles or atmospheric aerosols affect us every day in all kind of aspects like health, environment and even our economy so, for this reason, the study of aerosols is an important research field. To measure the properties of these particles, different technologies already exist and are commercially available. However, there are two factors that limit these technologies: resolution and when the data is processed. We often see only one being chosen, leaving the other aside so, when you have resolution, it takes time to get the results; and on the contrary, when you have real time detectors, you lose resolution. The system described on this thesis is the beginning of a device that will fill that gap, providing both resolution and real time analysis. In this document, I will first present a small theoretical chapter where a special focus on light scattering will be given; the second chapter will have its focus on the detector where everything will be described in detail; the third chapter will present the results achieved by this system; the fourth chapter will present three applications that obtained real data using this system during my internship and the final chapter will expose the conclusions and future prospects for this project. Since when I arrived, one system was almost prepared, my role in this project took part from here, starting with the alignments techniques development and testing, optimization and minor improvements, programing and data analysis and finally testing and repairing in different environments. At the end, the system was able to detect different particle sizes with great precision

Towards individual aerosol Particle identification using advanced laser spectroscopic techniques

This thesis presents the development and use of an optical device designed for aerosol analysis in different environments. We expose and analyze the results of an organized expedition to better understand the role of marine aerosols on the global climate. This device also enabled us to carry out a campaign of real-time measurements of individual particles from urban aerosols. By integrating advanced techniques of fluorescence depletion spectroscopy (pump-probe) into a portable device, we were able to distinguish, with high selectivity, the aerosols containing amino acids compared to those containing polycyclic hydrocarbons. Finally, we tested this device under real conditions of use. In addition, a comparative test using particle impaction on a filter was performed to confirm the existence of biological material by traditional biochemical analysis. This first test in real conditions of use has allowed us to demonstrate the benefits and limitations of this type of device and builds a foundation for future applications

Discriminating Bio-aerosols from Non-Bio-aerosols in Real-Time by Pump-Probe Spectroscopy

The optical identification of bioaerosols in the atmosphere and its discrimination against combustion related particles is a major issue for real-time, field compatible instruments. In the present paper, we show that by embedding advanced pump-probe depletion spectroscopy schemes in a portable instrument, it is possible to discriminate amino acid containing airborne particles (bacteria, humic particles, etc.) from poly-cyclic aromatic hydrocarbon containing combustion particles (Diesel droplets, soot, vehicle exhausts) with high selectivity. Our real-time, multi-modal device provides, in addition to the pump-probe depletion information, fluorescence spectra (over 32 channels), fluorescence lifetime and Mie scattering patterns of each individually flowing particle in the probed air

Real-time monitoring of bacterial and organic pollution in a water stream by fluorescence depletion spectroscopy

We demonstrate an approach for a real-time, consumable-free optical system operating on a liquid jet which can be easily derived from the water distribution infrastructure. We apply a pump-probe scheme based on the acquisition and nanosecond manipulation of UV-excited fluorescence to increase the selective identification of bacterial against organic pollutants in water

ATLANTIC ANTS: a data set of ants in Atlantic Forests of South America

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