Time-resolved mid-infrared dual-comb and Fourier transform spectroscopy for plasma diagnostics
[S.l.] : [S.n.]
Number of pages
Radboud University, 14 december 2021
Promotor : Harren, F.J.M. Co-promotores : Khodabakhsh, A., Cristescu, S.M.
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Molecular and Laser Physics
SubjectMolecular and Laser Physics
The time-dependent monitoring of fast chemical reactions in the mid-infrared wavelength region is important for various fundamental and applied research areas such as physical chemistry, plasma/combustion analysis, astronomy, biophysics, and environmental research. Broadband, time-resolved absorption spectroscopy offers the possibility to simultaneously monitor the time-dependent parameters of chemical reactions, such as concentrations of intermediate/final products, free radicals, and ions, as well as branching ratios, reaction rate coefficients, temperature, and number densities of molecular excited-states. In addition, compact broadband mid-infrared supercontinuum (SC) sources are emerging, with broad spectral coverage, high brightness, and high spatial coherence. Therefore, the aim of this thesis is two-fold. On the one hand, the development of a time-resolved mid-infrared dual-comb spectrometer (DCS) for plasma diagnostics between 3.1-3.6 μm (3200-2800 cm-1), which yielded promising results in the species specificity and quantification of the hydrocarbon methane and ethane plasmas. On the other hand, the development of a mechanical Fourier Transform Spectrometer (FTS) combined with mid-infrared Supercontinuum (SC) sources that have a high repetition frequency in the wavelength region of 2-4 μm (5000-2500 cm-1) and 1.5-10.5 μm (6600-950 cm-1). The latter combination offered a simple way of sensitive spectroscopy with wide spectral bandwidth and good spectral resolution for the environmentally important molecules, i.e., methane, nitric oxide, sulfur dioxide, and the multispecies detection of ethane and ethyl acetate.
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