Growth, spectral and optical characterization of a novel nonlinear optical organic material: d-Alanine dl-Mandelic acid single crystal

• Published in: Journal of molecular structure 2017-04, Vol.1134, p.67-77
• Main Authors: Jayaprakash, P., Mohamed, M. Peer, Caroline, M. Lydia
• Format: Article
• Language: English
• Subjects: Activation energy; Nonlinear optics; Nuclear magnetic resonance; Optical absorbance; Photoluminescence; Thermal stability
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2016.12.026

An organic nonlinear optical single crystal, d-alanine dl-mandelic acid was synthesized and successfully grown by slow evaporation solution growth technique at ambient temperature using solvent of aqueous solution. The unit cell parameters were assessed from single crystal X-ray diffraction analysis. The presence of diverse functional groups and vibrational modes were identified using Fourier Transform Infra Red and Fourier Transform Raman spectral analyses. The chemical structure of grown crystal has been identified by Nuclear Magnetic Resonance spectroscopic study. Ultraviolet–visible spectral analysis reveal that the crystal has lower cut-off wavelength down to 259 nm, is a key factor to exhibit second harmonic generation signal. The electronic optical band gap and Urbach energy is calculated as 5.31 eV and 0.2425 eV respectively from the UV absorption profile. The diverse optical properties such as, extinction coefficient, reflectance, linear refractive index, optical conductivity was calculated using UV–visible data. The relative second harmonic efficiency of the compound is found to be 0.81 times greater than that of KH2PO4 (KDP). The thermal stability of the grown crystal was studied by thermogravimetric analysis and differential thermal analysis techniques. The luminescence spectrum exhibited two peaks (520 nm, 564 nm) due to the donation of protons from carboxylic acid to amino group. The Vickers microhardness test was carried out employing one of the as-grown hard crystal and there by hardness number (Hv), Meyer's index (n), yield strength (σy), elastic stiffness constant (C11) and Knoop hardness number (HK) were assessed. The dielectric behaviour of the as-grown crystal was analyzed for different temperatures (313 K, 333 K, 353 K, and 373 K) at different frequencies. [Display omitted] •UV spectrum reveals that the title compound can be used as a nonlinear optical material.•Urbach energy of DADLMA is found to be 0.2425 eV.•The SHG efficiency is 0.81 times that of KDP.•The Photoluminescence spectral study revealed the electron excitation of the grown crystal.•The crystal belongs to a soft material category.