Spaceborne sensors (1983-2000 AD): A forecast of technology

A technical review and forecast of space technology as it applies to spaceborne sensors for future NASA missions is presented. A format for categorization of sensor systems covering the entire electromagnetic spectrum, including particles and fields is developed. Major generic sensor systems are related to their subsystems, components, and to basic research and development. General supporting technologies such as cryogenics, optical design, and data processing electronics are addressed where appropriate. The dependence of many classes of instruments on common components, basic R&D and support technologies is also illustrated. A forecast of important system designs and instrument and component performance parameters is provided for the 1983-2000 AD time frame. Some insight into the scientific and applications capabilities and goals of the sensor systems is also given

Measurements of the group delay and the group delay dispersion with resonance scanning interferometer

We developed a method for group delay and group delay dispersion measurements, based on location of interference resonance peaks. Such resonance peaks can be observed in transmittance or in reflectance when two mirrors are placed parallel to each other and separated by a thin air spacer. By using a novel approach, based on simultaneous processing of the data acquired for different spacer distances we obtained reliable results with high resolution. Measurements were performed both in transmittance and reflectance layouts depending on the reflectivity of the mirror to be measured. The developed method allows dispersion measurements of ultraviolet mirrors and ultra-broadband mirrors spanning more than one optical octave to be performed

Construction of a femtosecond pump-probe spectroscopy system and experiments on the photochemistry of 1-diazo-indan-2-one derivates

The aim of this work was the investigation of 3-diazo-2-indolinone photoreactions as a part of the larger project concerning 1-diazo-2-indanone derivatives1. In a recent work, we published data on photochemistry of 3-diazo-3H-benzofuran-2-one2 and the study of 1-diazo-2-indanone is an ongoing project. The a - carbonyl carbene was identified by ultra fast pump probe spectroscopy experiments as the sole primary photoproduct of 3-diazo-2-indolinone in solution. It is formed within one picosecond upon irradiation. The possibility of rapid equilibration via intersystem crossing with its triplet state was discussed, based on the high-level ab initio calculations. The calculations predict a triplet ground state of studied compound in the gas phase. Ring-opening reaction of a singlet carbene is strongly favored over Wolff rearrangement reaction or oxirane formation by the calculations. The singlet carbene intermediate undergoes the ring opening reaction, yielding cumulenone in aprotic solvents, k ≈ 5.9 x 1010 s-1. The cumulenone structure of the intermediate was confirmed by step scan FTIR measurements in CD3CN. In aqueous solutions, the primary photoproduct is intercepted by water with a rate of kH2O ≈ 7 x 109 M-1 s -1. The yield of cumulenone is thus reduced with increasing water concentration. 3- Hydroxy-2-indolinone is the major product isolated after irradiation of 3-diazo-2- indolinone in aqueous solutions. It is formed by two reaction pathways depending on the water concentration in solution. They are either an O-H group insertion into the singlet carbene or alternatively hydration of the cumulenone. The O-H insertion is obviously favoured at higher water concentrations. We studied the mechanism of O-H insertion by laser flash photolysis technique. These experiments failed to detect any transient attributable to the enediol intermediate, which would be expected to show similar absorbance at 275 nm and ketonization kinetics as the enol of mandelic acid amide. The lack of such a transient ruled out the enol formation pathways of singlet carbene insertion into an O-H group. The pH rate profile has an acid-catalyzed portion kH + ≈ 2 x 1010 M-1s-1 followed by a complex uncatalyzed region. This behavior is in contradiction with all known mechanisms except the ylide formation followed by the proton transfer. This would suggest a long-lived ylide intermediate. Such a structure has not been observed yet. Therefore, for the complete understanding of the O-H insertion mechanism some additional experiments are necessary. The second goal of this work was the construction of the femtosecond pump-probe spectroscopy setup. The constructed setup allows the direct spectroscopic observation of the ultra short-lived intermediates in the wavelength range from 300 to 700 nm. The time resolution achieved is around 180 fs. The repetition rate of the setup is 426 Hz and the time resolved spectra can be measured within 1.8 ns time window. Other projects, in which I have been involved during my PhD study, were the investigation of photochemical reaction mechanisms of 2-nitrobenzyl compounds3, the study of an excited state intramolecular proton transfer in 2-naphtol and the study of energy and electron transfer in various Porphyrin - Deazaflavin systems

Construction of a femtosecond pump-probe spectroscopy system and experiments on the photochemistry of 1-diazo-indan-2-one derivates

The aim of this work was the investigation of 3-diazo-2-indolinone photoreactions as a part of the larger project concerning 1-diazo-2-indanone derivatives1. In a recent work, we published data on photochemistry of 3-diazo-3H-benzofuran-2-one2 and the study of 1-diazo-2-indanone is an ongoing project. The a - carbonyl carbene was identified by ultra fast pump probe spectroscopy experiments as the sole primary photoproduct of 3-diazo-2-indolinone in solution. It is formed within one picosecond upon irradiation. The possibility of rapid equilibration via intersystem crossing with its triplet state was discussed, based on the high-level ab initio calculations. The calculations predict a triplet ground state of studied compound in the gas phase. Ring-opening reaction of a singlet carbene is strongly favored over Wolff rearrangement reaction or oxirane formation by the calculations. The singlet carbene intermediate undergoes the ring opening reaction, yielding cumulenone in aprotic solvents, k ≈ 5.9 x 1010 s-1. The cumulenone structure of the intermediate was confirmed by step scan FTIR measurements in CD3CN. In aqueous solutions, the primary photoproduct is intercepted by water with a rate of kH2O ≈ 7 x 109 M-1 s -1. The yield of cumulenone is thus reduced with increasing water concentration. 3- Hydroxy-2-indolinone is the major product isolated after irradiation of 3-diazo-2- indolinone in aqueous solutions. It is formed by two reaction pathways depending on the water concentration in solution. They are either an O-H group insertion into the singlet carbene or alternatively hydration of the cumulenone. The O-H insertion is obviously favoured at higher water concentrations. We studied the mechanism of O-H insertion by laser flash photolysis technique. These experiments failed to detect any transient attributable to the enediol intermediate, which would be expected to show similar absorbance at 275 nm and ketonization kinetics as the enol of mandelic acid amide. The lack of such a transient ruled out the enol formation pathways of singlet carbene insertion into an O-H group. The pH rate profile has an acid-catalyzed portion kH + ≈ 2 x 1010 M-1s-1 followed by a complex uncatalyzed region. This behavior is in contradiction with all known mechanisms except the ylide formation followed by the proton transfer. This would suggest a long-lived ylide intermediate. Such a structure has not been observed yet. Therefore, for the complete understanding of the O-H insertion mechanism some additional experiments are necessary. The second goal of this work was the construction of the femtosecond pump-probe spectroscopy setup. The constructed setup allows the direct spectroscopic observation of the ultra short-lived intermediates in the wavelength range from 300 to 700 nm. The time resolution achieved is around 180 fs. The repetition rate of the setup is 426 Hz and the time resolved spectra can be measured within 1.8 ns time window. Other projects, in which I have been involved during my PhD study, were the investigation of photochemical reaction mechanisms of 2-nitrobenzyl compounds3, the study of an excited state intramolecular proton transfer in 2-naphtol and the study of energy and electron transfer in various Porphyrin - Deazaflavin systems

Analytical techniques: A compilation

A compilation, containing articles on a number of analytical techniques for quality control engineers and laboratory workers, is presented. Data cover techniques for testing electronic, mechanical, and optical systems, nondestructive testing techniques, and gas analysis techniques

Development of experimental and instrumental systems to study biological systems

Chapters 1-4 of this thesis describes the development of an experimental system to measure diffusion-limited reaction kinetics in a biological environment. About 100 years ago, the relationship between reaction rate and diffusion in homogenous solution, ie water or buffer, was described as a linear relationship by Smoluchowski. Applying this theory naively would suggest that since the diffusion coefficients drop by factors of 4-100 then the rates of reaction would drop by the same amount. However, recent theory and simulations suggest that this does not hold. Even though biological diffusion coefficients drop to 0.1-20% of that in buffer, these recent studies show that the reaction kinetics are much more weakly affected by the biological environment. Due to the lack of experimental evidence for biological diffusion, there is a great need for information in this area. Here, I describe a protein system, exogenous to E. coli¸ that will form a dimer in the presence of a small molecule. ^ I also describe the development of a new type of multivariate hyperspectral Raman instrument (MHI); the instrument is developed for use to study biological tissues and for high speed cell sorting applications. The new instrument design has a large speed advantage over traditional Raman instrumentation for rapid chemical imaging. While the MHI can reproduce the functionality of a traditional Raman spectrometer, its true speed advantage is realized after pre-training on known sample components. The MHI makes use of a spatial light modulator as a programmable optical filter that can be programmed with filters based on multivariate signal processing algorithms, such as PLS, in order to rapidly detect chemical components and create chemical maps. Chapters 5-8 of this thesis describe the development and construction of the MHI, as well as provide proof-of-concept experimental results demonstrating its functionality

Environmental stress evaluation of Coffea arabica L. leaves from spectrophotometric fingerprints by PCA and OSC-PLS-DA

The effects of hydric stress and sunlight access conditions on metabolic compounds in coffee leaves were investigated utilizing statistical mixture design extractor solvents. PCA and OSC-PLS-DA chemometric methods were used to analyze UV-visible spectra of irrigated and non-irrigated Coffea arabica L. leaves from low (80 cm, light exposed) strata. The first latent variable of the OSC-PLS-DA score plot perfectly discriminated extracts of 34 calibration and 14 validation samples of irrigated and non-irrigated leaves. Higher spectral signals observed at the 410, 505, 535, 607 and 665 nm wavelengths are attributed to conjugate double bond pigments, mainly pheophytin a, indicating that non-irrigated conditions are more stressful than irrigated ones for this species. No significant difference was found for leaf sample extracts with varying light access conditions12842514257CAPES - Coordenação de Aperfeiçoamento de Pessoal e Nível SuperiorCNPQ - Conselho Nacional de Desenvolvimento Científico e Tecnológicosem informaçãosem informaçãoThe authors acknowledge the financial support of CNPq, CAPES, INCT – Energia e Ambiente and Fundação Araucária as well as for the scholarships granted. The Agronomic Institute of Paraná (IAPAR) is thanked for supplying the coffee leaf samples used in this wor