Educational Background:

PhD, University of California, Berkeley, 1985 AB, Harvard University, 1979

Awards:

• National Merit Scholar • Phi Beta Kappa • IR-100 Award for Most Significant Technological Advances • University of California Abramson Fellow • Weizmann Institute Bantrell Postdoctoral Fellow • University of Illinois IBM Postdoctoral Fellow • Lilly Foundation Teaching Fellow

Research Description:

My group has combined advances in methodologies with applications of solid-state nuclear magnetic resonance experiments to important and interesting real materials systems. When we are lucky, these two spheres of interest overlap.

Often materials characterization consists of measurements of various bulk properties. This phenomenological approach has certain drawbacks. Where a rational strategy for improving particular properties is desired, a detailed understanding of the local, atomic-level structure and/or dynamic modes, and their relationship to bulk properties, is needed. Our goal is to develop such a microscopic understanding of local structure and, often more importantly, dynamics. Solid-state NMR has the particular advantage in such studies that the absence of long-range order-often a feature of modern systems based on polymers or alloys-does not substantially degrade the quality of the information ultimately derived. Furthermore, the technique is atom-specific with resolution sufficient to differentiate between similar chemical environments.

We have been particularly interested in non-chemical approaches to polymer modification, exploiting an approach based on modification of the surrounding physical environment. Under suitable conditions, a wide variety of polymers-both polar and nonpolar, naturally entangled and more crystalline-can be intercalated into layered solids. These polymer nanocomposites often exhibit novel properties that can be conveniently mediated by controlling subtle guest-host interactions. Solid-state NMR is a powerful tool for monitoring the microscopic differences, static and dynamic, that characterize these composites.

We also have been actively pursuing the question of how nontraditional irradiation schemes, such as shaped or "noisy" (incoherent) rf fields, might be exploited in magnetic resonance. Many such experiments require lower power than do traditional methods of observing NMR spectra, thus have broader applicability. Additionally, these experiments have the advantage of clarifying the connections between magnetic resonance and optical spectroscopies.

Selected Publications:

Michal, C. A.; Simmons, A. H.; Chew, B. G. M.; Zax, D. B.; Jelinski, L. W. Presence of phosphorus in Nephila clavipes dragline silk. Biophys. J. 1996, 70, 489.

Liao, M.-Y.; Zax, D. B. Analysis of signal-to-noise ratios for noise excitation of quadrupolar nuclear spins in zero field. J. Phys. Chem. 1996, 100, 1483.

Wong, S.; Vaia, R.; Giannelis, E. P.; Zax, D. B. Dynamics in a PEO-based nanocomposite polymer electrolyte probed by solid state NMR. Sol. State Ionics 1996, 86-88, 547.

Zax, D. B. Field-dependent isotropic shifts and limitations to linewidths in solid state NMR: A floquet treatment. J. Chem. Phys. 1996, 105, 6616.

Hijirida, D. H.; Do, K. G.; Michal, C.; Wong, Sl.; Zax, D.; Jelinski, L. W. 13C NMR of Nephila clavipes major ampullate silk gland. Biophys. J. 1996, 71, 3442.

Wong, S.; Zax, D. B. What do NMR linewidths tell us? Dynamics of alkali cations in a PEO-based nanocomposite polymer electrolyte, ion dynamics in some nanocomposite polymer electrolytes. Electrochimica Acta 1998, 42, 3513.

Yang, D.-K.; Atkins, J. E.; Lester, C. C.; Zax, D. B. New developments in NMR using noise spectroscopy. Molecular Physics in press.

Yang, D.-K.; Zax, D. B. Bandwidth extension in noise spectroscopy, submitted.