The proposed project involves theoretical and computational studies of the electron dynamics in semiconductor and metal nanostructures. The prime focus will be placed on the understanding of the role of many-body correlations and quantum confinement effects in the optical properties that can be measured using various spectroscopy techniques.
The first part of the project will address spin dynamics of excitons in quantum wells in a strong magnetic field. In a magnetic field, the role of interactions is enhanced and spin dynamics of multi-exciton states is entangled with Coulomb correlations. Of particular interest are the relaxation processes that involve transitions between bright and dark exciton states, facilitated by spin-orbit interactions, and the coherent spin dynamics that can be measured with spin-sensitive nonlinear optical spectroscopy.
The second part of the project is related to spectroscopy of many-body excitations in modulation-doped quantum wells. In many-electron systems, the absorption of a photon is accompanied by shakeup of many-body excitations that give rise to novel features in optical spectra. Of particular interest are the processes that result in excitation of more than one electron-hole pair upon absorption of a single photon. Such processes, that are many-body analogues of impact ionization, can have significant applications such as increased efficiency of solar cells.
The third part of the project involves plasmon-enhanced spectroscopies in metal nanostructures, in particular, in hybrid systems comprised of a molecule or semiconductor dot in the vicinity of metal nanoparticle arrays. Optical properties of such systems are dominated by interactions between the internal degrees of a dot and surface collective excitations in the metal. Here we are interested in quantum rather than electromagnetic effects that arise when the molecule/dot is in a close proximity to metal nanostructure.
Intellectual merit The proposed research will be carried out in areas of high current interest and will contribute to the solution of several outstanding issues. For example, an accurate description of plasmon-enhanced optical characteristics is relevant for a variety of applications, such as nanoparticle-based sensors and other biomedical devices. Theoretical description of many-body processes in nanostructures is a rather challenging task, complicated by strong quantum-size effects, that requires nonperturbative approaches. The completion of the project will involve a variety of analytical and numerical methods. The results will be compared to the available experimental data and disseminated in the form of publications and conference presentations.
Broader impact Active participation of undergraduate student assistants is planned throughout entire project duration. Being a historically black predominantly undergraduate institution, Jackson State University primarily serves the educational needs of the Mississippi largest urban community. The completion of the project will enhance research and education opportunities for undergraduate students predominantly from underrepresented groups by exposing them to the new concepts and methods of nanoscience.
This grant will support theoretical research at an undergraduate historically black university. The research will investigate the properties of electrons in nanoscale structures of metals or semiconductors. In particular, novel optical properties will be studied. Students will participate in the research.
