Neste trabalho é apresentada uma nova geometria e os critérios de projeto para dispositivos de espectrometria de mobilidade iônica, com objetivo de aumentar a relação entre sinal e ruído detectados pelos eletrômetros que compõem a região de detecção, quando associado à ionização baseada em descargas elétricas que tipicamente emitem maior interferência eletromagnética em relação a outros tipos de ionização. A geometria e os critérios de projeto foram estabelecidos com o auxílio do simulador de trajetórias iônicas SIMION versão 8.1 e comparada com espectrômetros de mobilidade iônica do estado-da-arte. Os resultados das simulações dos dispositivos foram avaliados por meio dos testes estatísticos não-paramétricos de Iman-Davenport e Holm. O resultado indicou que a geometria proposta apresentou compatibilidade com as melhores características dos espectrômetros atuais com confiança estatística a 95 %. Na sequência a geometria proposta foi simulada, fabricada e testada para detecção dos íons de: tolueno - C7H8 (C5H5+, C6H5+, C7H7+), propanol - C3H8O (CH3+, CH3O+, C2H3+, C2H4O+, C2H5O+, C3H6+, C3H7+, C3H7O+) e água - H2O (H+, HO+, H2+, O+). Os picos de corrente iônica detectada nos eletrômetros indicaram coerência com as trajetórias simuladas para estes conjuntos de íons. Além disso, os resultados experimentais apresentaram um aumento na relação entre sinal e ruído para a nova geometria proposta que foi validada pelo teste de comparação pareada não-paramétrico de Wilcoxon a 95 % de confiança estatística. / In this work, a new geometry and a design criteria for ion mobility spectrometry devices was presented, aiming to increase the signal-to-noise ratio detected by electrodes of the detection region, when associated with ionization based on electrical discharges. The new geometry and the design criteria were established in the SIMION version 8.1 (an ionic trajectory simulator) and compared with the state-of-art ion mobility spectrometers. The results from device simulations were evaluated using the non-parametric statistical test of Iman-Davenport and Holm. The result indicated that the proposed design criteria presented compatibility with the best characteristics of current spectrometers with statistical evidence at 95%. The proposed geometry was simulated, fabricated and tested for the following solvents: toluene - C7H8 (C5H5+, C6H5+, C7H7+), propanol - C3H8O (CH3+, CH3O+, C2H3+, C2H4O+, C2H5O+, C3H6+, C3H7+, C3H7O+) and water - H2O (H+, HO+, H2+, O+). The peaks of ion current detected in the electrometers occurred at approximate positions of the simulated trajectories for these sets of ions. In addition, the experimental data showed an increase in the signal-to-noise ratio for the proposed new geometry that was validated by the test statistic of Wilcoxon signed rank at 95% statistical confidence.

Neste trabalho é apresentada uma nova geometria e os critérios de projeto para dispositivos de espectrometria de mobilidade iônica, com objetivo de aumentar a relação entre sinal e ruído detectados pelos eletrômetros que compõem a região de detecção, quando associado à ionização baseada em descargas elétricas que tipicamente emitem maior interferência eletromagnética em relação a outros tipos de ionização. A geometria e os critérios de projeto foram estabelecidos com o auxílio do simulador de trajetórias iônicas SIMION versão 8.1 e comparada com espectrômetros de mobilidade iônica do estado-da-arte. Os resultados das simulações dos dispositivos foram avaliados por meio dos testes estatísticos não-paramétricos de Iman-Davenport e Holm. O resultado indicou que a geometria proposta apresentou compatibilidade com as melhores características dos espectrômetros atuais com confiança estatística a 95 %. Na sequência a geometria proposta foi simulada, fabricada e testada para detecção dos íons de: tolueno - C7H8 (C5H5+, C6H5+, C7H7+), propanol - C3H8O (CH3+, CH3O+, C2H3+, C2H4O+, C2H5O+, C3H6+, C3H7+, C3H7O+) e água - H2O (H+, HO+, H2+, O+). Os picos de corrente iônica detectada nos eletrômetros indicaram coerência com as trajetórias simuladas para estes conjuntos de íons. Além disso, os resultados experimentais apresentaram um aumento na relação entre sinal e ruído para a nova geometria proposta que foi validada pelo teste de comparação pareada não-paramétrico de Wilcoxon a 95 % de confiança estatística. / In this work, a new geometry and a design criteria for ion mobility spectrometry devices was presented, aiming to increase the signal-to-noise ratio detected by electrodes of the detection region, when associated with ionization based on electrical discharges. The new geometry and the design criteria were established in the SIMION version 8.1 (an ionic trajectory simulator) and compared with the state-of-art ion mobility spectrometers. The results from device simulations were evaluated using the non-parametric statistical test of Iman-Davenport and Holm. The result indicated that the proposed design criteria presented compatibility with the best characteristics of current spectrometers with statistical evidence at 95%. The proposed geometry was simulated, fabricated and tested for the following solvents: toluene - C7H8 (C5H5+, C6H5+, C7H7+), propanol - C3H8O (CH3+, CH3O+, C2H3+, C2H4O+, C2H5O+, C3H6+, C3H7+, C3H7O+) and water - H2O (H+, HO+, H2+, O+). The peaks of ion current detected in the electrometers occurred at approximate positions of the simulated trajectories for these sets of ions. In addition, the experimental data showed an increase in the signal-to-noise ratio for the proposed new geometry that was validated by the test statistic of Wilcoxon signed rank at 95% statistical confidence.

In this dissertation, different approaches have been employed to address the quest of understanding the formation and growth mechanisms of carbon-containing molecular ions with relevance to astrochemistry. Ion mobility mass spectrometry and DFT computations were used to investigate how a second nitrogen in the pyrimidine ring will affect the formation of a covalent bond between the benzene radical cation and the neutral pyrimidine molecule, after it was shown that a stable covalent adduct can be formed between benzene radical cation and the neutral pyridine. Evidence for the formation of a more stable covalent adduct between the benzene radical cation and the pyrimidine is reported here. The effect of substituents on substituted-benzene cations on their solvation by an HCN solvent was also investigated using ion mobility mass spectrometry and DFT computations were also investigated. We looked at the effect of the presence of electron-withdrawing substituents in fluorobenzene, 1,4 di- fluorobenzene, and benzonitrile on their solvation by up to four HCN ligands, and compared it to previous work done to determine the solvation chemistry of benzene and phenylacetylene by HCN. We report here the observed increase in the binding of the HCN molecule to the aromatic ring as the electronegativity of the substituent increased. We also show in this dissertation, DFT calculations that reveal the formation of both hydrogen-bonded and electrostatic isomers, of similar energies for each addition to the ions respectively. The catalytic activity of the 1st and 2nd row TM ions towards the polymerization of acetylene done using the reflectron time of flight mass spectrometry and DFT calculations is also reported in this dissertation. We explain the variation in the observed trend in C-H/C-C activity of these ions. We also report the formation of carbide complexes by Zr+, Nb+, and Mo+, with the acetylene ligands, and show the thermodynamic considerations that influence the formation of these dehydrogenated ion-ligand complexes. Finally, we show in this dissertation, a novel ionization technique that we employed to generate ions that could be relevant to the interstellar and circumstellar media using the reflectron time of flight mass spectrometry.