Characterization of an NLO crystal - Diphenlamine

The organic nonlinear optical crystal of Diphenylamine(DPA) has been successfully grown by slow evaporation technique. Functional groups of the Diphenylamine(DPA) were confirmed by FTIR. The optical transmittance of DPA recognized by UV-Vis-NIR studies and the lower cutoff wavelength of the single crystal and thus it could be perfomed as NLO material. The NLO property of the DPA crystal has been confirmed by second harmonic generation (SHG) technique and the efficiency of the grown crystal over KDP and urea. The thermal stability of DPA crystal has been studied by thermogravimetric analysis(TGA) and differential thermal analysis(DTA). The mechanical strength of the crystal has been measured by Vickers Microhardenss testing. A study on the Mulliken atomic charges, the electronic properties were performed by time-dependent DFT (TD-DFT) approach. The stability of molecule has been analyzed by using NBO/NLMO analysis. The molecular electrostatic potential has been mapped primarily for predicting sites and relative reactivities towards electrophilic and nucleophilic attack. The calculated HOMO and LUMO energies show that charge transfer occurs within these molecules. The temperature dependance of thermodynamic properties has been analyzed. Global and local reactivity descriptors have been calculated in order to have a deep insight into the molecule for further applications.