ON THE SPECTRAL AND DYNAMIC EFFECTS OF NEAR-NODAL MOLECULE EMF COUPLING ARISING FROM PERMANENT DIPOLE-MOMENTS

The spectral and temporal consequences of a non-zero difference d(kj) = mu(kk) - mu(jj) between the permanent dipole moments mu(jj) of two s tates involved in a transition are investigated for two-and three-leve l model molecular systems interacting with a continuous wave laser. Th e field strengths are such that the molecule-EMF couplings for the sys tems are near-nodal. The interesting spectral and dynamic effects of n ear-nodal molecule-EMF couplings are unique to transitions where d(kj) not equal 0, relative to d(kj) = 0 These effects are studied using ex act Floquet calculations and analytical solutions in the two-level rot ating wave approximation (RWA). The RWA discussion of near-nodal molec ule-EMF couplings, how they are achieved, and their effects, is quite general and applies to any two-level model of a dipolar molecule. The actual values of the laser parameters required to achieve a molecule-E MF coupling node depend on the specific molecule under consideration. This is illustrated with explicit two-and three-level molecular models , based on the S-0 and S-1 states of 1-[p-(N,N-dimethyl- amino)phenyl] -4-(p-nitrophenyl)-1,3-butadiene. Although the held strengths required to achieve near-nodal couplings are too large for the quantitative ap plication of the analytical results, the two-level RWA solutions are c rucial for the qualitative interpretation and prediction of the exact laser-molecule behaviour. The examples illustrate that the near-nodal effects of d(kj) not equal 0, as predicted by the two-level RWA and ve rified by the two-and three-level exact calculations, persist when nei ghbouring energy levels are present in the model.