Rozprawy doktorskie na temat „Chirped pulse microwave spectroscopy”
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Kadiwar, Gautam. "Chirped-Pulse Fourier Transform Microwave Spectroscopy of Fluoroiodoacetonitrile and Chloropentafluoroacetone". Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc84230/.
Pełny tekst źródłaGrubbs, Garry Smith II. "Investigating Molecular Structures: Rapidly Examining Molecular Fingerprints Through Fast Passage Broadband Fourier Transform Microwave Spectroscopy". Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc67988/.
Pełny tekst źródłaPowoski, Robert A. "Molecular Structure Analyses of Asymmetric Hydrocarbon Liquid Compounds in the Gas Phase Using Chirped-pulse Fourier Transform Microwave Spectroscopy: Acyl Chlorides and Perfluorinated Acyl Chlorides". Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc103374/.
Pełny tekst źródłaOsseiran, Noureddin. "Spectroscopic characterization of molecules of atmospheric interest : internal dynamics and microsolvation with hydrogen sulfide (H2S)". Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR062.
Pełny tekst źródłaBiogenic volatile organic compounds (BVOCs), and especially monoterpenes (C10H16), are molecules naturally occurring in the atmosphere, which have been linked to the formation of secondary organic aerosol (SOA). They can alter the physical and chemical properties in the atmosphere, have negative effects on human health and contribute to climate change. There exists a strong relationship between the structure of a molecular system and the inter- and intramolecular interactions present on the molecular scale.Hence, having in-depth information about the gas phase structure and internal dynamics of these molecules, or their molecular complexes, is important to better understand their reaction pathways and complexation patterns.The synergic combination of quantum chemical calculations and Fourier transform microwave (FTMW) spectroscopy has been shown to be a reliable approach to examine the conformational landscape, structure and internal dynamics of several types of molecules of atmospheric interest, their oxidation products and their complexes. In the framework of this thesis, we have applied this theoretical-experimental approach to characterize the complexes of two monoterpenoids: fenchol (C10H18O) and fenchone (C10H16O) with another atmospheric contaminant: the H2S molecule. The gas phase stable conformations were identified in the pure rotational spectrum with the supportof ab initio and DFT calculations. A comparative analysis of the observed complexes with their water analogues confirmed the presence of weaker hydrogen bonds. On top of that, we observed a large amplitude motion, that was qualitatively described. The stabilizing non-covalent interactions of the two complexes were also evaluated.In a similar manner, and within the same general context, we also characterized the conformational landscape and methyl internal rotation in the case of limona ketone (C9H14O), which is a biogenic volatile organic compounds (BVOC) originating from the oxidation limonene. The experimental barrier height of the methyl torsion showed some deviation from the calculated values, which pushed toward a more thorough examination, that revealed the presence of an intermolecular interaction.The second part of this thesis was dedicated to the construction and evaluation of a broadband chirped pulse FTMW spectrometer, operating in the range 6-18 GHz. A detailed technical description of the spectrometer is given herein. Moreover, the preliminary tests performed to evaluate the performance of the spectrometer are reported
Colombo, Anthony P. (Anthony Paul). "Chirped-pulse millimeter-wave spectroscopy, dynamics, and manipulation of Rydberg-Rydberg Transitions". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82169.
Pełny tekst źródłaThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 131-138).
The chirped-pulse millimeter-wave (CPmmW) technique is applied to transitions between Rydberg states, and calcium atoms are used as the initial test system. The unique feature of Rydberg{Rydberg transitions is that they have enormous electric dipole transition moments: ~5 kiloDebye at n* ~45, where n* is the eective principal quantum number. After polarization by a mm-wave pulse in the 70{84 GHz frequency region, the excited transitions re-radiate free induction decay (FID) at their resonant frequencies, and the FID is heterodyne-detected by the CPmmW spectrometer. Data collection and averaging are performed in the time domain. The spectral resolution is ~100 kHz. Because of the large transition dipole moments, the available mm-wave power is sucient to polarize the entire bandwidth of the spectrometer (12 GHz) in each pulse, and high-resolution survey spectra may be collected. Both absorptive and emissive transitions are observed, and they are distinguished by the phase of their FID relative to that of the excitation pulse. With the combination of the large transition dipole moments and direct monitoring of transitions, dynamics are observed, such as transient nutations from the interference of the excitation pulse with the polarization that it induces in the sample. Transient nutations also provide information about the sample, such as the dipole moment and the number density of Rydberg states. Since the waveform produced by the mm-wave source may be precisely controlled, states with high angular momentum may be populated by a sequence of pulses while recording the results of these manipulations in the time domain. Also, the superradiant decay of the Rydberg sample is probed both directly through FID and indirectly using photon echoes. Prospects for further manipulations, such as adiabatic rapid passage, composite pulses, and optical/mm-wave stimulated Raman adiabatic passage, are evaluated. The application of the CPmmW technique to transitions between Rydberg states of molecules is discussed.
by Anthony P. Colombo.
Ph.D.
Klein, Ethan Avram. "A buffer gas cooled molecular beam apparatus for chirped pulse millimeter wave spectroscopy". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98781.
Pełny tekst źródłaCataloged from PDF version of thesis.
Includes bibliographical references (pages 34-36).
An apparatus that utilizes buffer gas cooling to produce slow atomic (Ba, Ca) and molecular (BaF, CaF) beams is constructed. In-cell temperatures of 20 ± 0.25K are achieved with chamber cooldown times of under two hours. Laser Induced Fluorescence (LIF) spectra of BaF and CaF confirmed thermalization of the molecular beam to the temperature of the buffer gas and additional hydrodynamic cooling to rotational and translational temperatures under 10K. Laser fluence effects on the intensity of barium and calcium ablation were studied and used to optimize laser parameters for maximum ablation of the desired species. A chirped pulse millimeter wave (CPmmW) setup was combined with the buffer gas cooling apparatus for combined laser and millimeter wave spectroscopy experiments of Rydberg states. LabVIEW programming is used for an internal temperature feedback system, raster scanning of the ablation target, as well as millimeter wave FID signal digital acquisition. Use of the apparatus for chirped pulse microwave spectroscopy of buffer gas cooled beams have led to orders of magnitude improvement in both the resolution and the reduction of time required to record molecular Rydberg spectra.
by Ethan Avram Klein.
S.B.
Shaver, Rachel Glyn. "The use of chirped pulse millimeter-wave spectroscopy in chemical dynamics and kinetics". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79274.
Pełny tekst źródłaCataloged from PDF version of thesis.
Includes bibliographical references (p. 51-53).
.Chirped-pulse millimeter wave (CPmmW) spectroscopy is a revolutionary technique that has taken advantage of advances in electronics to give high signal to noise broadband rotational spectra in a very short period of time that provides meaningful line intensities. We have implemented this technique in the 58 - 102 GHz range to study the rotational spectra of molecules with two heavy atoms. Photolysis (at 193 nm) and pyrolysis of vinyl cyanide have produced differing HCN and HNC vibrational population distributions. The photolysis experiment does not sample a collisional regime and the resulting spectra show excited states of HCN and HNC, whereas the pyrolysis experiment, which does sample a collisional regime, results in spectra that are devoid of vibrational satellites. This indicates that the intensities of vibrational satellite transitions sample the photolysis reaction only and not post-photolysis collisional effects. Mono-deuterated vinyl cyanide was photolyzed at 193 nm, in which all HCN/HNC are produced via a four-center mechanism and all DCN/DNC are produced via a three-center mechanism. The HCN and HNC products dominate, demonstrating the greater importance of the three-center mechanism. CPmmW spectroscopy is also a valuable tool in studying unimolecular and bimolecular reactions. We have studied the unimolecular decomposition of deuterated methyl nitrite which produces DNO products and bimolecular hydrogen abstraction reaction of NO with acetaldehyde resulting in HNO products. These reactions demonstrate the potential use of nitric oxide radical as a gas-phase catalyst to perform cracking of hydrocarbons and sugars.
by Rachel Glyn Shaver.
S.M.
Ganz, Thomas. "Supercontinuum generation by chirped pulse compression for ultrafast spectroscopy and broadband near-field microscopy". Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-148551.
Pełny tekst źródłaLiu, Weilin. "Real-time Interrogation of Fiber Bragg Grating Sensors Based on Chirped Pulse Compression". Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20289.
Pełny tekst źródłaBRAGA, PEDRO TOVAR. "TIME-RESOLVED OPTICAL SPECTROSCOPY FOR LASER CHIRP CHARACTERIZATION AND SELF-HETERODYNE GENERATION OF LFM AND NLFM MICROWAVE PULSES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35528@1.
Pełny tekst źródłaCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Este trabalho apresenta a geração de pulsos de microondas linearmente e não-linearmente modulados em frequência (LFM e NLFM) através da técnica fotônica de auto-heterodinagem. Ao utilizar eletrônica de baixa frequência para modular um diodo laser de feedback distribuído, a variação da portadora óptica no tempo (chirp) é observada, o que é causado predominantemente por efeito térmico. Este efeito, combinado com batimento auto-heteródino, foi capaz de produzir pulsos LFM com alto produto largura de banda-tempo (TBWP). Uma outra abordagem é necessária para geração de pulsos NLFM. Primeiro, é introduzida a técnica Espectroscopia Óptica Resolvida no Tempo para caracterização do chirp de um diodo laser. Em seguida, um estímulo de corrente em formato de função degrau é aplicado ao diodo laser para aquisição da função de transferência de seu chirp, H(s). Com a posse de H(s), uma simulação numérica foi usada para descobrir o estímulo necessário de corrente i(t) para obtenção de pulsos de microondas NLFM através da técnica de auto-heterodinagem. Os resultados experimentais coincidem com a simulação.
This work reports the photonic generation of both linear and non-linear frequency modulation (LFM and NLFM) microwave pulses through a self-heterodyne scheme. By using low-frequency electronics to drive a distributed feedback laser diode, optical chirping is generated predominantly by thermal effect. Combining laser chirping and self-heterodyning, LFM pulses with high time-bandwidth product (TBWP) were achieved. A different approach is required for generation of NLFM microwave pulses. First, for characterization of the laser diode chirp, it is introduced a technique named Time- Resolved Optical Spectroscopy. Then, by using a step-shaped current stimulus, the laser chirp transfer function H(s) was obtained. With knowledge on H(s), a numerical simulation produced the suitable current stimulus i(t) needed to generate NLFM microwave pulses through self-heterodyning. Experimental results agreed with the numerical simulations.
Ganz, Thomas [Verfasser], i Ferenc [Akademischer Betreuer] Krausz. "Supercontinuum generation by chirped pulse compression for ultrafast spectroscopy and broadband near-field microscopy / Thomas Ganz. Betreuer: Ferenc Krausz". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2011. http://d-nb.info/102665355X/34.
Pełny tekst źródłaSampson, Zaiyaan Begum. "Tungsten Telluride Quantum dot-based Biosensor for Alpha-Methylacyl CoA Racemase – An Emerging Prostate Cancer Biomarker". University of the Western Cape, 2019. http://hdl.handle.net/11394/7709.
Pełny tekst źródłaProstate cancer, commonly referred to as adenocarcinoma of the prostate, is the leading cause of cancer death in men in 46 countries, and it was estimated that by the end of 2018 there would approximately be 1.3 million new cases of prostate cancer worldwide. Currently, the Food and Drug Administration (FDA) approved biomarker for prostate cancer disease diagnostics Prostate Specific Antigen (PSA) is not specific to the disease itself but extends to other cases such as Benign Prostate Hyperplasia (BPH) a condition in which the prostate grows uncontrollably. This biomarker is then detected in blood samples via conventional methods which require a qualified individual to operate and are often time consuming. Examples of these methods are spectrophotometry and High Performance Liquid Chromatography (HPLC). Hence, a more efficient biomarker and method of detection is needed for prostate cancer disease diagnostics, as early detection of the disease means early treatment, which could ultimately save lives. Currently, an emerging biomarker for prostate cancer known as Alpha-Methyl CoA Racemase (AMACR) has shown to be more specific to the disease with advantages such as being a non-invasive biomarker. AMACR has been reported to be present in urine, and thus may be detected via a non-invasive method. This study proposed an economical, non-invasive electrochemical biosensor for the rapid detection of AMACR based on mercaptosuccinic acid capped tungsten telluride (MSA-WTe3) quantum dots (QDs). Nanomaterial has shown promise in terms of increasing the sensitivity and specificity of sensors. MSA-WTe3 QDs was successfully synthesized using easy, inexpensive method and was studied by various techniques such as High Resolution Transmission Electron Microscopy (HR-TEM) where the size was confirmed to be within the nanometer scale and was reported to be 2.65 nm with a good crystallinity. X-ray diffraction (XRD) confirmed the structural properties and chemical composition of the QDs and it is reported that the QDs are rich in both tellurium and tungsten and comprise of a hexagonal structure. Scanning Electron Microscopy (SEM) confirmed the successful immobilization of aptamer sequence specific to AMACR onto the electrode surface by showing a distinct conformational change when aptamers were introduced to the QDs under study. This study reports the successful detection of AMACR using an MSA-WTe3 QDs based aptasensor immobilized onto a screen printed glassy carbon electrode, with a detection limit of 0.35651 ng/mL and a limit of quantification calculated to be 1.08033 ng/mL.
Mead, Griffin John. "Chirped Pulse Microwave and Single-Shot Terahertz Spectroscopy Studies of Intermolecular Interactions". Thesis, 2021. https://thesis.library.caltech.edu/14018/4/mead_griffin_2020_thesis.pdf.
Pełny tekst źródłaWhile the glow of a sodium vapor lamp or the crisp reds in autumn leaves are eye-catching examples of transitions between atomic and molecular energy levels (hv ~2-3 eV), it is arguably the much lower energy, thermally populated intermolecular "bath" states (hv ~10⁻⁵-10⁻² eV) that contribute most directly to the physical properties of matter. Although invisible to the human eye, in this thesis we study fundamentals of these low-energy interactions with two complementary techniques: chirped pulse microwave spectroscopy and nonlinear single-shot terahertz (THz) Kerr effect spectroscopy.
In the first section, we apply chirped pulse-Fourier transform microwave (CP-FTMW) spectroscopy from 8-16 GHz to study fundamental hydrogen bonding motifs in gas phase alcohol water dimers. Hydrogen bonding is ubiquitous in nature and directly contributes to a range of phenomena from phase transitions in water to solvation of ions to enzymatic activity. Our focus on gas phase dimers reduces the spectral ambiguity arising in condensed phase samples, where inhomogeneous and homogeneous broadening can hamper observation of conserved intermolecular interaction motifs. The hydrogen bonding conformation of two alcohol-water dimers, n-propanol-water and isopropanol-water, were characterized. Both were found to adopt a shared water donor-alcohol acceptor conformation.
The following sections use nonlinear THz spectroscopy from 0.1-10 THz to investigate molecular dynamics in the condensed phase. We focus on halogenated methane liquids, whose intense intramolecular vibrational modes are commensurate in energy to the intermolecular bath states. One central goal of this section was developing a technique to more rapidly collect nonlinear, multi-dimensional data from liquid systems. To that end, we developed a single-shot measurement approach using a reflective nickel echelon mirror and a high frame rate camera. With this new device we achieved an order of magnitude reduction in experimental integration times. High resolution, nonlinear multi-dimensional THz studies of several halogenated methane liquids and materials were produced as a result. From these data, we identified important spectral contributions from the experimental instrument response function.
(5929736), Alicia O. Hernandez-Castillo. "BROADBAND MICROWAVE SPECTROSCOPY OF LIGNIN, BIOFUELS AND THEIR PYROLYSIS INTERMEDIATES". Thesis, 2019.
Znajdź pełny tekst źródła(8028629), Piyush Mishra. "Jet-Cooled Molecular Spectroscopy from the Microwave to the Ultraviolet". Thesis, 2019.
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