Characterization of the non-instantaneous contribution to the /spl chi//sup (3)/ in different liquids and glasses using femtosecond chirped pulses

Summary form only given. Separation of the electronic and nuclear (i.e. non-instantaneous) contributions in the time domain is usually difficult using femtosecond time-resolved optical techniques. To overcome this problem, it was suggested that the dominant mechanism could be identified by studying Kleinman symmetry of the nonlinear susceptibility tensor. In an isotropic medium far from material resonance, it implies R=/spl chi//sub XXXX//sup (3)/=/spl chi//sub XYYX//sup (3)/=3. For instantaneous processes, this ratio has been measured in different gases. In the paper we show for the first time that in liquid and glasses the ratio R of the non-instantaneous contribution of /spl chi//sup (3)/ depends on the studied sample.