High Resolution Infrared Spectroscopy of Slit-Jet Cooled Radicals and Ions

<p>This thesis presents high-resolution spectra of supersonically-cooled organic radicals in\&nbsp;<span style="line-height: 1.6em;">the mid-infrared, the details and design of the instruments necessary to obtain the spectra,\&nbsp;</span><span style="line-height: 1.6em;">and the theory to understand the spectra and the larger context of the results. Specifically,\&nbsp;</span><span style="line-height: 1.6em;">four organic radicals are studied: singly-deuterated methyl radical (CH2D), phenyl radical\&nbsp;</span><span style="line-height: 1.6em;">(C6H5), hydroxymethyl radical (CH2OH), and ethynyl radical (C2H). All of the spectroscopic\&nbsp;</span><span style="line-height: 1.6em;">studies presented use an existing mid-infrared high-resolution spectrometer with a frequency\&nbsp;</span><span style="line-height: 1.6em;">precision of better than 10 MHz. The radicals are generated using a discharge to dissociate\&nbsp;</span><span style="line-height: 1.6em;">a neutral precursor and form the radicals. The discharge is localized at the orifice of a slit\&nbsp;</span><span style="line-height: 1.6em;">supersonic expansion, which cools the radicals to around 20 K and allows for sub-Doppler\&nbsp;</span><span style="line-height: 1.6em;">spectral resolution. In addition to the description of the existing spectrometer, the design,\&nbsp;</span><span style="line-height: 1.6em;">construction, and successful testing of a new, automated mid-infrared spectrometer is presented.\&nbsp;</span><span style="line-height: 1.6em;">The new spectrometer is based upon difference frequency generation of a scanning\&nbsp;</span><span style="line-height: 1.6em;">Ti:Sapphire laser and a single-frequency Nd:YAG laser to create high-resolution mid-infrared\&nbsp;</span><span style="line-height: 1.6em;">radiation. The new system speeds up data-taking by fully automating the scanning process.</span></p>
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University of Colorado Boulder
Boulder, CO
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