Experimental and theoretical investigation of optical nonlinearities in (nitrovinyl)-1H-pyrazole derivative.

This work reports on the optical nonlinearities of a newly synthesized pyrazole derivative, namely (E)-1-(4-chlorophenyl)-4-(2-nitrovinyl)-1H-pyrazole. The Z-scan technique with femtosecond laser pulses was used to determine the two-photon absorption (2PA) cross-section spectrum, which presents a maximum of 67 GM at 690 nm. We have combined hyper-Rayleigh scattering (HRS) experiments and second-order Møller-Plesset perturbation theory (MP2) calculations to study the first hyperpolarizability (ß(HRS)). It was found that the MP2/6-311+G(d) model, taking into account solvent and dispersion effects, provides the ß(HRS) value of 40×10(-30) cm(5)/esu for the compound, in good agreement with the experimental result of 45±2×10(-30) cm(5)/esu.