Density matrix calculation of surface enhanced Raman scattering for silver nanoshells coated with p-mercaptoaniline
Gibson, Joshua Wayne
Johnson, Bruce R.
Master of Science
The tremendous increase in Raman-scattered photons seen in Surface-Enhanced Raman Scattering (SERS) has led to its adoption as a common analytical laboratory tool in spite of lingering questions about the phenomenon. One recent example is the demonstration by Jackson, et al., of SERS for silver nanoshells each consisting of an inner silica sphere encased in a silver shell. In concert with these experiments, the current investigation is directed at quantum mechanical calculation and modeling of the SERS signals to be expected for silver nanoshells coated by molecules based on ab initio calculations on an AgPMA salt model with the thiol bonding to silver rather than an H atom as in the free PMA molecule. We take the information from these calculations and consider a density matrix formalism including the effects of the strong electromagnetic near fields around the metal surface, the molecules' orientation and energy, and the associated Raman spectra.