Development of Newly Built Chirped-pulsed Fourier Transform Microwave (CP-FTMW) Spectrometer for Studying Biomolecules in the Gas Phase

摘要

Recent advances in the technology of oscilloscopes and digital waveform generators have made it possible to shorten collection times, increase scan bandwidths and improve the overall sensitivity of microwave spectroscopy. Thus, microwave spectroscopy has become a powerful tool for the determination of the structures of molecules. The Pate group, at the University of Virginia, has developed a new technique called chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy that has the ability to measure the broadband pure rotational spectra of large molecules. Working in collaboration with the Pate group, we have developed, at the University of Pittsburgh, a small version of the UVa spectrometer. This version of the CP-FTMW spectrometer uses a narrower bandwidth pulse, ~500 MHz, which makes it possible to record a spectrum using lower power amplifiers at significantly reduced cost. Using this new spectrometer the pure rotational spectra of N,N΄-dimethylaniline, 4,4'-dimethylaminobenzonitrile, o-toluidine, m-toluidine, 4-fluorobenzyl alcohol, valeric acid, and δ-valerolactam were collected and studied. From these spectra, their three-dimensional structure, bonding properties, and intermolecular interactions were determined.