Synthesis, bulk growth, polarizability and nonlinear optical properties of γ-glycine single crystals

The role of sodium acetate, sodium nitrate, sodium hydroxide and malonic acid as additives in assisting the nucleation of γ‐polymorph from solution has been investigated. For the first time large dimensional bulk single crystals of γ‐glycine have been grown at the optimized concentration of the additives by the top seeded slow cooling technique. The bulk growth of single crystals elucidates well the unidirectional growth characteristics and the existence of merohedral twinning in γ‐ glycine. Polarizability, plasmon energy and Fermi energy has been evaluated for the first time for γ‐glycine single crystals based on an analytical approach. Structural affirmation of the nucleated polymorph has been carried out by Powder x‐ray diffraction and the thermal characteristics of the nucleated polymorph are well revealed by Differential Scanning Calorimetry. The non linear optical characteristics of γ‐glycine studied by Kurtz and Perry technique revealed increased SHG efficiency with the highest of about 2.2 in the presence of malonic acid compared to the standard Potassium dihydrogen orthophosphate (KDP). Large dimensional single crystals of γ‐glycine have been grown for the first time. γ‐glycine nucleated in presence of malonic acid revealed highest SHG efficiency. Parallel head to tail alignment in the structure of γ‐glycine leads to higher SHG efficiency. For first time analytical elucidation of optical parameters of γ‐glycine is reported. Phase transition from γ to α‐polymorph observed in DSC, confirms the type of polymorph.