Clifford Russell Bowers
Associate Professor of Chemistry

Department of Chemistry
University of Florida

VOICE: (352) 846-0839

EMAIL: bowers@chem.ufl.edu

HOMEPAGE: http://www.chem.ufl.edu/~bowers/

Research Interests

The Bowers research group specializes in developing new methods of detection of nuclear magnetic resonance which exploit couplings of electrons and nuclei in optical and electronic transport processes. A broad range of applications are facilitated by these new methods, including low-dimensional quantum systems such as semiconductor quantum wells and other multilayer thin film structures, metal films, chemically active surfaces, gas clathrates, and biological macromolecules.

One of the primary methods employed by us is known as spin exchange optical pumping. In this method, a nonequilibrium electron spin polarization of the ground or excited state can be prepared by optical excitation according to the selection rules for optical transitions. The electron spin polarization can be transferred to the nuclei via hyperfine relaxation. We are conducting spin exchange optical pumping experiments in gases and solid state systems. Spin exchange optical pumping with rubidium vapor can produce large quantities of highly polarized xenon-129 or helium-3. In our lab, 50,000 fold NMR signal enhancements have been observed, corresponding to a xenon-129 spin polarization of about 50%. This NMR signal enhancement has been applied to the study of binding sites in proteins and to the mechanism of the reaction of xenon with ice crystals to form xenon clathrate hydrate. Hyperpolarized xenon-129 is also being employed in microimaging of materials.

Recent Publications

1. A. Patel, C.R. Bowers, ¡°Detection of Optical Pumping Enhanced Dipolar Nuclear Spin Order in GaAs and InP by Two-Dimensional Nuclear Magnetic Resonance,¡± submitted for publication (2003).

2. B. Jagadeesh, A. Prabhakar, M.H.V. Ramana Rao, A.C. Kunwar and C.R. Bowers, ¡°Probing anisotropic environment of thermotropic liquid crystal using 129Xe NMR spectroscopy,¡± submitted for publication (2003).

3. Eugene Olshanetsky, Manyam Pilla, Joshua D. Caldwell, Shu-chen Liu, and Clifford R. Bowers, ¡°Temperature dependence and mechanism of electrically detected ESR at the n=1 filling factor of a two-dimensional electron system in GaAs quantum wells,¡± Phys. Rev. B 67, 165325 (2003) [PDF]

4. Bhavin B. Adhyaru, Novruz G. Akhmedov, Alan R. Katritzky, Clifford R. Bowers, ¡°Solid-State NMR Spectroscopy Characterization of Sepia melanin, Sepia Free Acid, and Human Hair Melanin in Comparison with Several Model Compounds,¡± Magnetic Resonance in Chemistry, 41: 466?474 (2003). [PDF]

5. Anthony L. Zook, Bhavin B. Adhyaru, Clifford R. Bowers, ¡°High Capacity Production of >65% Spin Polarized Xenon-129 for NMR Spectroscopy and Imaging,¡± Journal of Magnetic Resonance 159, 177 ?184 (2002) [PDF].

6. Clifford R. Bowers, ¡°Sensitivity Enhancement Utilizing Parahydrogen,¡± in Encyclopedia of Nuclear Magnetic Resonance: Supplementary Volume, John Wiley & Sons, Ltd, pp. 750-770 (2002).

7. Vincent J. Storhaug, Florian Liebig, Clifford R. Bowers, ¡°Spin Exchange Optical Pumping Enhanced 129Xe NMR Spectroscopy of SF6/Xe and Acetone-d6/Xe Mixed Type-II Clathrate Hydrates,¡± J. Phys. Chem., 106, 2884-2891 (2002) [PDF]

8. Paul J. Carson, C. Russell Bowers and Daniel P. Weitekamp, ¡°The PASADENA Effect at a Solid Surface: High-Sensitivity Nuclear Magnetic Resonance of Hydrogen Chemisorption,¡± J. Am. Chem. Soc. 123, 11821-11822 (2001). [PDF]

9. Y.-Y. Lin, S. Ahn, N. Murali, W. Brey, Clifford R. Bowers, Warren S. Warren, "High Resolution, > 1 GHz NMR in Unstable Magnetic Fields,"Phys. Rev. Lett, 85 3732-3735 (2000).[PDF]

10. Sergey A. Vitkalov, Clifford R. Bowers, Jerry A. Simmons, John L. Reno,"ESR Detection of optical dynamic nuclear polarization in GaAs/AlGaAs quantum wells at unity filling factor in the quantum Hall effect," Phys. Rev. B, 61, 5447-5451 (2000). [PDF]