Accession Number : ADA304224

Title :   Molecular Nonlinear Optical Susceptibilities in Condensed Phases.

Descriptive Note : Final rept. 15 Nov 92-14 Nov 95,

Corporate Author : ROCHESTER UNIV NY DEPT OF CHEMISTRY

Personal Author(s) : Mukamel, Shaul

PDF Url : ADA304224

Report Date : NOV 1995

Pagination or Media Count : 11

Abstract : A microscopic theory for the nonlinear optical response and susceptibilities of molecular materials with localized and delocalized electronic states (e.g. molecular assemblies, conjugated polymers, aggregates and monolayers) was developed. The theory, which properly accounts for many body effects, is based on the derivation of coupled reduced equations of motion for the material variables, which determine the optical response. The present formulation maps the calculation of optical nonlinearities onto solving the dynamics of coupled nonlinear oscillators and overcome the difficulties associated with the local field approximation. an operational definition of the nonlinear coherence size Nc, which controls the cooperative enhancement of the optical response is developed. A real space representation of the optical response of conjugated polyenes is developed by using the Wannier representation to derive equations of motion for coupled two site oscillators representing correlated electron hole pairs. The resulting elementary excitations are shown to be intermediate between the molecular (Frenkel) and the semiconductor (wannier) excitons, and clearly resemble charge transfer excitons. Theoretical analysis of resonant and off resonant femtosecond pump probe absorption experiments on polydiacetylene-para-toluene sulfonate (PTS) was carried out using a 3-mode Brownian oscillator model for the nuclear dynamics. The role of spectral diffusion process was explored.

Descriptors :   *POLYMERS, *EXCITONS, *ELECTROMAGNETIC SUSCEPTIBILITY, COUPLING(INTERACTION), OPTICAL PROPERTIES, COMPUTATIONS, EQUATIONS OF MOTION, FORMULATIONS, THEORY, COHERENCE, PHASE, SPECTRA, ELECTRONIC STATES, CHARGE TRANSFER, DIFFUSION, CONDENSATION.

Subject Categories : Polymer Chemistry
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE