PHOTOPHYSICAL AND SECOND-ORDER NONLINEAR PROPERTIES OF PUSH-PULL FLUORINATED 4-(DICYANOMETHYLENE)-PYRANES

摘要

The photophysical and nonlinear properties of some push-pull fluorinated 4-(dicyanomethylene)-pyranes using the steady-state and time-resolved picosecond spectroscopies with an electric-field-induced second-hamionic-generation technique have been investigated. Strong fluorescence quenching and large shifts of time-resolved transient picosecond spectra on going from nonpolar to polar solvents are connected with effective charge transfer interactions of polar singlet excited molecules with a polar environment. The high second-order polarizability (β=260·10~(-30) esu for one of the investigated push-pull pyranes (PTFDN) allows to propose using such kind of molecules in the development of second-harmonic-generation elements.