A New Generation of Chirped Pulse Rotational Spectroscopy with Applications to Structure Determination and Astrochemistry

Chirped-pulse rotational spectroscopy is emerging as a powerful technique for molecular detection and characterization. Using this broadband technique, a multicomponent mixture can be quantitatively analyzed quickly, and the unique characteristics of rotational spectroscopy allow for the structural determination of all of the species in the sample. In the past few years, instrumental upgrades have made a qualitatively new class of problems accessible to chirped-pulse rotational spectroscopy. The instrumental improvements made in our laboratory in the past few years, along with techniques to aid in the assignment and characterization of complex spectra, are described. The new capabilities of this spectrometer are applied to two types of problems. The first is in the direct structure determination of large molecules and molecular clusters through the measurement of isotopically labeled species, particularly in the size regime (>10 non-hydrogen atoms) where weak interactions play a crucial role in overall structure, and where electronic structure theory begins to struggle in accurately capturing the effects of various competing forces. The second application is to astrochemistry, where broadband spectroscopic techniques are needed to partner with broadband radio astronomical facilities in understanding the complex chemistry that occurs in the interstellar medium. This thesis will also describe ways in which the principles of chirped-pulse spectroscopy can be applied in the millimeter and submillimeter regions, which open up a variety of both research and commercial applications.

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