Spectroscopic investigation and non linear optical activity study on 7,7,8,8-tetra cyano quino dimethane

FT-IR and FT-Raman spectra of 7,7,8,8-tetracyanoquinodimethane(TCNQ) was recorded and analyzed. The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers of TCNQ and its related compounds have been performed using density functional theory(DFT) method with 6-311G(d,p) basis set. The detailed interpretation of the vibrational spectra has been carried out with the aid of Molvib program. The TD-DFT calculation has been compared with UV–Vis spectrum with different solvents. HOMO-LUMO energy gap, local softness and electrophlicity indices for selected atomic sites of the TCNQ and its related compounds were determined. The intermolecular interaction in the TCNQ were confirmed by using Hirshfeld surfaces. The NLO activity of molecule was confirmed by SHG analysis. The surface resistance and third-order nonlinear optical property of the crystal were studied by laser induced surface damage threshold and Z-scan techniques respectively using Nd:YAG laser with wavelength 532 nm.