Welcome
Our current research program involves three main areas:
-
Using pulsed-beam, Fourier transform spectroscopy to determine the accurate 3-D molecular structures and electronic charge distributions of transition metal complexes, hydrogen-bonded complexes and small molecules.
-
Construction, development and optimization of a very large pulsed-beam, Fourier transform spectrometer to further improve the sensitivity and resolution of measurements of larger molecules and complexes.
-
Development and utilization of laser photodissociation and discharge molecular beam sources for new measurements on radicals, reactive molecules and unstable reaction products.
The complete, accurate, 3-D structures obtained using gas-phase microwave spectroscopy are very helpful in understanding reaction mechanisms and characterizing the bonding and electronic structures of molecules. There are many important examples in chemistry (catalysis) biochemistry (enzymes) and biology (DNA) where a detailed knowledge of molecular structures has provided the key to understand the details of how reactions proceed.
Microwave spectroscopy has been the most accurate and precise method for measuring the bond lengths and angles in free molecules for many years. Thousands of examples of microwave structure measurements have been reported over the past 45 years. The development of the pulsed-beam, Fourier transform spectrometer (by W. H. Flygare and T. Balle) provided greatly improved sensitivity and resolution, extending this technique to hydrogen-bonded complexes and opening the door for work on larger molecules.
Our Flygare-Balle spectrometer has been in operation at the University of Arizona since 1983. Beginning in 1988, this spectrometer was used to obtain the first microwave measurements of structures and electronic properties of many transition metal complexes. Most of the published microwave structures of this important class of molecules have come from this work at the University of Arizona. Only a few examples had been reported earlier, using lower-resolution microwave methods.
Ongoing Projects
1-4 GHz Microwave Spectrometer
To be able to make spectroscopic measurements on larger molecules we built the World's first pulsed Fourier-transform spectrometer that operates in the 1-4 GHz range. The longer wavelength requires bigger Fabry-Perot cavity which resulted in impressive dimensions of the spectrometer. The picture above shows the open vacuum chamber, with one of the mirrors (big grey dish) inside. More details on this project can be found at this link.