Solvent Effect Of Molecular Spectra In Bulk Solution And At Liquid/Liquid Interface

This dissertation includes three parts. Based on electrostatics, the modified non-equilibrium solvation theory by our group is introduced in the first part. The defects existing in conventional non-equilibrium solvation theories are pointed out. Under the approximation of point-dipole and sphere cavity model, the modified continuum model is applied to the calculation of spectral shift in bulk solution, and the modified spectral shift expressions have different forms compared with Lippert-Mataga equation. Particularly, the result from the modified non-equilibrium solvation theory is half of that from the previous theory for the Stokes shift. At the same approximate conditions, the analytical expressions of spectral shift at interface are obtained for the molecules at the heterogeneous interface by using electrostatics. Besides, the multipole expansion method, which can calculate more accurately the spectral shift energy, is briefly introduced. As we know, the molecular radius is a key factor in calculating the spectral shift, and the methods used to measure it in experiment and theory have been briefly reviewed. The popular methods to calculate the dipole moments and Mulliken populations of the ground and excited states are introduced, such as HF, DFT and CASSCF methods.In order to verify the validity of the modified spectral shift expressions, two systems, PRODAN (6-propionyl-2-(N,N-dimethylamino) naphthalene) and DMABN (4-(N,N-dimethylamino)benzonitrile) are investigated in the second part. The geometry optimizations of both systems are carried out at the levels of B3LYP/6-31+G* and B3LYP/6-31+G**. The structures of the excited states are...