Associate Professor, Ph.D. UC Santa Barbara (1995)

Education

Research Interests

• Biophotonic, electro-optic and spintronic materials: ultrafast optical and terahertz studies

Research is underway to develop and understand novel optical and electronic materials to enable the technologies of all optical computing, spintronic devices and quantum computing. These efforts include biophotonic materials, electro-optic materials and ferromagnetic semiconductor materials.

The technological revolution of the 20th century was based on semiconductor technology; however, limitations in size and function are rapidly approaching. As an alternative, the optical and electrical properties of biosystems, their emerging tailorability through mutagenisis and their ability to self assemble into regular periodic structures, has created a new materials science field based on biosystems. We are investigating photoactive proteins and the interface between biomolecules and conventional semiconductor systems through ultrafast optical/terahertz studies. In addition to the technological applications, these studies of the relationship between molecular conformational dynamics and biological function will contribute to the understanding of signal transduction in biological systems. This research is part of an NSF interdisciplinary doctoral fellowship program (IGERT) at UB (http://www.photonics.buffalo.edu/IGERT/vision.htm).

In order to realize all optical computing, optical equivalents to electronic components are being developed. These include logic, storage and routing elements based on electro-optic materials. The response of these materials is determined by the conformational dynamics of the crystalline structures. We measure the ultrafast dynamics of electro optic and ferroelectric nanoparticle materials developed at the Institute for Lasers, Photonics and Biophotonics at the University at Buffalo (http://www.photonics.buffalo.edu/).

Adding the control of the spin state in electronic systems opens new avenues for electronic and optical devices. Among these applications are three state logic, optical computing and quantum computing. Such spin state control could be realized by ferromagnetic semiconductor materials. We are studying the high frequency transport properties of these materials to determine the nature of electronic response in these novel 2D systems.

Selected Publications

1. "Terahertz Time domain spectroscopy of the M intermediate state of Bacteriorhodopsin", S. Whitmire, A. G. Markelz, J. R. Hillebrecht, and R. Birge, Proceedings of the 26th International Conference on Infrared and Millimeter Waves, Toulouse, France Sept. 10-14 2001
2. "Pulsed Terahertz Spectroscopy of DNA, Bovine Serum Albumin and Collagen between 0.06 to 2.00 THz", A. G. Markelz, A. Roitberg, and E. J. Heilweil, Chem. Phys. Lett. 320, 42 (2000).
3. "Temperature Dependent THz Output from Semi-Insulating GaAs Photoconductive Switches", A. G. Markelz and E. J. Heilweil, Appl. Phys. Lett. 72, 2229 (1998).
4. "Energy relaxation time in InAs/Al1-xGaxSb quantum wells", A. G. Markelz, N. G. Asmar, E. G. Gwinn, and Berinder Brar, Appl. Phys. Lett. 72, 2439 (1998).
5. "Impact Ionization in InAs quantum wells with Far Infrared illumination", A. G. Markelz, N. G. Asmar, E. G. Gwinn, and Berinder Brar, Appl. Phys. Lett. 69, 3975 (1996).