Actions of Various Amino Acid Additives on the Growth , NLO , Optical and Physical Properties of Potassium Acid Phthalate ( Kap ) Crystals

Introduction Potassium hydrogen phthalate also called as potassium acid phthalate [KAP, K(C6H4COOH-COO)] is a semi organic salt that belongs to orthorhombic class of alkali acid phthalate series [1]. The crystal structure of KAP is ionic consisting of potassium ions and alkali phthalate ions and it belongs to the Pca21 space group [2]. KAP crystals are widely used as analyzers in the long wavelength range of the Xray spectrum and as monochromators in various highresolution X-ray instruments. At low temperatures KAP crystals are diamagnetic along all the three main crystallographic directions [3] and they exhibit piezoelectric, pyroelectric, ferroelectric, elastic and nonlinear optical properties with long term stability in devices [2, 4, 5]. The metallic ion dopants (Fe 3+ , Cr 3+ , Zn 2+ , Cu 2+ , etc.) in the KAP crystals are reported to induce significant changes in optical, ferroelectric and non linear optical behaviors [6-8]. Monica Enculescu has studied the effect of rhodamine 6G, coumarine 6 and polyvinylpyrrolidone (PVP) on KAP crystals using solution growth method [2, 9]. It was reported that the dopants enhance the second harmonic generation (SHG) efficiency of KAP. Parthiban et al. [8] also reported that the Zn 2+