Growth and studies on structural, optical & time-domain terahertz spectroscopy of l-cysteine hydrochloride monohydrate single crystal for nonlinear optical applications

In recent days, nonlinear optical materials are getting attention because of their potential applications in the area of lasers, optical sensing and terahertz etc. A good quality single crystal of l-cysteine hydrochloride monohydrate was grown by slow evaporation solution technique using deionized water as a solvent with a time span of 25 days. The powder X-ray diffraction reveals the orthorhombic and non-centrosymmetric P212121 space group of the as-grown crystal. FTIR and FT-Raman analyses confirmed the existence of all possible vibrational modes inside the host molecule. The optical bandgap of the as-grown crystal was calculated to be 3.8 eV from UV–Vis spectroscopy which reveals the wide bandgap nature of the material. The emission of blue light (449 nm) upon an incident of UV–Vis light (320 nm) shows the luminescence behavior of the crystal. The Electric field amplitude, absorption and refractive index were analyzed by Terahertz time-domain spectroscopy.