Spectroscopic and non-linear optical studies of two novel optical limiters from dichloroaniline family crystals: 3,4-Dichloroaniline and 3,5-dichloroaniline

Abstract Two organic crystals of the isomeric forms of dichloroanilines such as 3, 4-dichloroaniline (3,4-DCA) and 3, 5-dichloroaniline (3,5-DCA) were grown by slow evaporation method and characterized by various analytical techniques. The vibrational normal modes of the samples were theoretically predicted using the scaled quantum mechanical force field procedures with the DFT level calculation and the potential energy distributions of the individual modes were estimated using the normal coordinate analysis. Fermi doublets and Evans holes were identified in the vibrational spectra of samples. The nuclear relaxation contribution to the vibrational polarizabilities and hyperpolarizabilities for the normal modes of the molecules were quantitatively estimated using the DFT method. The results of the calculated NLO responses showed that the vibrational mean contributions to the static polarizabilities and hyperpolarizabilities were smaller than the corresponding electronic contributions for the molecules. The Kurtz and Perry powder SHG efficiencies were measured and both samples have generated the second-harmonics of the fundamentals. The open-aperture Z-scan study results proposed the superior optical limiting property of 3,5-DCA with respect to 3,4-DCA.