Nonlinear Optical Response of Confined Excitons in Molecular and Semiconductor Nanostructures.
Final rept. 1 Jul 94-31 Jul 97,
ROCHESTER UNIV NY DEPT OF CHEMISTRY
Pagination or Media Count:
The nonlinear optical response of Semiconductor Quantum Wells, Organic Superlattices and Conjugated Polyenes was calculated using collective electronic coordinates, which represent the joint dynamics of electron-hole pairs. The use of femtosecond four-wave mixing spectroscopy to probe the nature of electronic States and Exciton and free-carrier interactions in these systems was explored. The formation and dynamics of quasiparticles involving electrons dressed by nuclear deformations in conjugated polymers was studied. The Si natures of charged solitons, neutral solitons, polarons and bipolarons in the resonant and off-resonant optical susceptibilities of conjugated polymers were calculated using the Pariser-Parr-Pople PPP model. The optical response was obtained by solving equations of motion for the reduced single-electron density matrix, derived using the time dependent Hartree-Fock TDHF approximation. The approach relates the optical Signals directly to the dynamics of charges and bond orders electronic coherences induced by the radiation field and uses only ground-state information, thus avoiding the explicit calculation of excited states. A Density-Matrix-Electronic-Oscillator representation was employed for calculating the third order nonlinar A optical response of semiconductor quantum dots in the limits of weak and strong exciton confinement. The nonlocal electrodynamics of arrays of quantum dots was treated exactly using Green function techniques. The research program included the development of software which uses the newly developed algorithms in the design of new optical materials.
- Numerical Mathematics
- Quantum Theory and Relativity