The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a fifteen-month research fellowship by Dr. Mary E. Mulcahy to work with Dr. Alejandro Fainstein at Instituto Balserio Physics in Rio Negro, Argentina. Support for this project comes from the Office of International Science and Engineering's (OISE) Americas Program.
Dr. Fainstein's laboratory is part of a collaboration with scientists in Argentina, New Zealand, and the UK exploring a new method for making Surface Enhanced Raman Spectroscopy (SERS) active substrates. To make these substrates, metal is electrochemically deposited in the presence of commercially available, submicron-sized polystyrene latex spheres, to produce macroporous, metallic films. Initial experiments with the films show they exhibit better signal reproducibility and are more robust than traditional, electrochemically roughened metal surfaces used in SERS experiments. To understand the fundamental principles which govern the enhancement observed with the new substrates, it would be useful to selectively deposit molecules in specific areas within the cavities. To accomplish this, layered metal films will be produced to give cavities of a particular metal with one or more rings of a different metal interspersed in them. The deposition of alkanethiols, which adsorb onto different metal surfaces at distinct potentials, can be then be spatially controlled. The active area inside the nanocavities and how the area changes with cavity size will be examined. Continuity and uniformity of the thin layers of deposited metal will need to be verified before the technique is actually employed for the nanocavities. The effect that a mixed gold/silver nanocavity will have on the plasmon generated within the nanocavity will also be addressed. Finally, the limit of detection and surface selection rules that can be expected from using the macroporous films as SERS substrates will also be explored.
