The International Research Fellowship Program enables U.S. scientists and engineers to conduct three 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 twenty-two-month research fellowship by Dr. Joshua A. Henry to work with Dr. Bengt H. Kasemo at Chalmers Institute of Technology in Goteborg, Sweden.
The PI's dissertation research focused on the effect of surface chemistry on the quality factor, or Q, of micromechanical resonators. The Q, which is essentially the number of cycles an oscillator completes before damping out, must be high for applications requiring great force sensitivity and narrow bandwidths (e.g. sensors and cell phones, respectively), however researchers have noted decreasing Q with decreasing resonator size. The PI's research has demonstrated that a surprising amount of this drop in Q, in silicon oscillators, is attributable to the chemical termination of the surface. They have characterized a number of surface chemistries and demonstrated that surface-induced losses in Q are particularly acute at the nanoscale. Surfaces are also important in optical phenomena at the nanoscale. The energy in light-induced excitations in metal nanoparticles, called surface plasmons, have the potential to carry out useful processes such as single molecule spectroscopy, photocatalytic cleaning of gas emissions and water, and improving solar energy conversion via photovoltaic cells or solar-driven decomposition of water to H2. At the same time these phenomena contain a number of challenging physics questions, related to the involved excitation and de-excitation mechanisms, including nanoparticle (surface) plasmons, their decay into electron-hole pairs and interaction of the latter with HOMO/LUMO orbitals of adsorbed molecules. In this study the dependence of these mechanisms on particle size, morphology and interparticle spacing will be probed using a combination of nanofabrication, chemistry, high-resolution microscopies and surface sensitive spectroscopies.
Chalmers University has the facilities and expertise necessary to complete this study. Technologies that conserve or generate meaningful amounts of energy renewably still face significant innovation challenges. The scientific strengths of other countries must be leveraged to innovate the necessary technologies. Research in photovoltaic (solar) cells and related technologies in European countries is one of those strengths. Taking advantage of this strength to enable several potential biological and environmental applications is at the center of this proposal. The application aims of this project are executed in collaboration with some of the top group in the world in catalysis, photovaltaics and biosensing.
