This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
With this award from the Major Research and Instrumentation (MRI) program, Professor Brooks H. Pate of the University of Virginia, David W. Pratt of the University of Pittsburgh and Steven T. Shipman of New College of Florida have submitted a proposal in response to the MRI-R2 solicitation to construct a 3rd Generation Chirped-Pulse Fourier Transform Microwave spectrometer (CP-FTMW) for applications in molecular structure determination. The proposed instrument will advance microwave spectroscopy for the analysis of conformational flexible molecules, molecular complexes and chemically reactive species such as ions and radicals. In addition, powerful new double-resonance techniques using fully shapeable microwave pulses produced by a high-speed arbitrary waveform generator will be designed and implemented. These techniques will make it possible to use the spectrometer's performance gains to speed the analysis of spectra, not just the acquisition of spectra.
The CP-FTMW technique exploits advances in high-speed digital electronics to achieve excellent speed and sensitivity in obtaining molecular rotational spectra. Analysis of the spectra provides detailed structural parameters for the molecules, ions and radicals under investigation. Structural information is the sine qua non necessary to understand chemical properties and reactivity. The development of this spectrometer will train undergraduate and graduate students in the construction and use of modern instrumentation.
A facility for broadband molecular rotational spectroscopy has been created that augments the research programs of scientists in the field of molecular spectroscopy and provides state-of-the-art education projects to undergraduate students. A new design for chirped-pulse Fourier transform microwave spectrometers has been implemented. As part of the instrument development, researchers worked with Tektronix to develop high-throughput methods for signal averaging in commercial digital oscilloscopes. This technology is now offered as a product option on the Tektronix high-speed digital oscilloscopes. A design for low-frequency microwave spectroscopy (2-8 GHz) was implemented that extends the technique of molecular rotational spectroscopy into a new region that is well-suited to the studies of large molecules and clusters. In addition, following a recent report of a new way to measure the chirality of a molecule using rotational spectroscopy (D. Patterson, M. Schnell, and J.M Doyle, Nature 497, 475- 478 (2013)), we have developed a new pulsed-spectroscopy approach for making chiraltiy measurements in the 2-8 GHz instrument. This instrument design is offered commericially through BrightSpec, Inc. One major goal of the project was to make the advanced techniques of rotational spectroscopy available to the broader scientific community to augment their research programs. Following instrument commisioning in 2012, the facility has been used by 27 external research groups (and 24 young researchers in these groups). These collaborators include groups from Canada, UK, Poland, Spain, Switzerland, and France. Notable projects have included the studies fo molecular complexes and a wide-ranging study of the structures of water clusters. The structural information obtained from the measurements provides important experimental benchmark data for the development of computational chemistry methods. The water cluster experiments have produced several important advances including the detection of isomers of water hexamer, an understanding of the role that quantum effects play in the hexamer energetics, and the role that "cooperativity" plays in the hydrogen bonding of water. The second goal for the facility is to introduce modern instrumentation into the undergraduate physical chemistry curriculum. A series of physical chemistry lab projects has been created that covers topics in the fundamentals of spectroscopy, hydrogen bonding in chemistry, the detection of molecules in the interstellar medium, and the determination of absolute configuration (chirality). These laboratory projects have been evaluated in the undergraduate physical chemistry laboratory course at the Univerity of Virginia and will be offered to students and faculty at other institutions where sutdents will be able to operate the instrument via internet control. The facility instrument has also been used in a summer undergraduate research program that is a collaboration with the National Radio Astronomy Observatory and the VA NC LSAMP program. Over the course of the project, 12 students from underrepresented minority groups in sicence have used the facility to perform research in the field of astrochemistry.
