Bromo-and chloro-derivatives of dibenzylideneacetone: Experimental and theoretical study of the first molecular hyperpolarizability and two-photon absorption

•The first molecular hyperpolarizability (βHRS) of two DBA molecules was investigated.•Two-photon absorption cross-section (σ2PA) spectra of two DBA molecules were measured.•Calculated βHRS and σ2PA showed good accordance with the experimental results. This work reports the study of the second- and third-order nonlinear optical properties of two dibenzylideneacetone derivatives: (1E,4E)-1,5-bis(4-bromophenyl)penta-1,4-dien-3-one (4-DBDBA) and (1E,4E)-1,5-bis(4-chlorophenyl)penta-1,4-dien-3-one (4-DCDBA) in dichloromethane solution. The nonlinear optical properties investigated were the first molecular hyperpolarizability and the two-photon absorption (2PA) cross-section by using the hyper-Rayleigh scattering (HRS) and Z-scan techniques respectively. The values of the first molecular hyperpolarizability obtained by HRS (βHRS) were 25×10-30 cm4 statvolt-1 for 4-DBDBA whereas for 4-DCDBA was 27×10-30 cm4 statvolt-1. The peak value for 2PA cross-section by the spectral measurement was around 24 GM for 4-DBDBA and 17 GM for 4-DCDBA. In addition, quantum chemical calculations were performed to support the interpretation from experimental results.