A study of the non-linear refractive index (n(2)) and the non-linear absorp
tion coefficient(alpha(2)) of molecules containing mesoionic rings in solut
ion has been carried out using the Z-scan technique with 70 ps at 532 nm. T
he second molecular hyperpolarizabilities, gamma, were inferred and the exp
erimental results are in a good qualitative agreement with our semi-empiric
al AM1-TDHF calculations. Optical Kerr gate measurements with 60 fs pulses
at 800 nm allowed us to identify an ultra-fast response time for the third-
order non-linearity. These results indicate that mesoionic rings are promis
ing materials for photonic applications. (C) 1999 Elsevier Science B.V. All
rights reserved.