Unidirectional crystal growth, luminescence and scintillation characteristics of t-stilbene single crystals

Temperature gradient based unidirectional solution growth set-up was specially designed to felicitate the growth of unidirectional crystals of t-stilbene with cylindrical dimension of 6 cm x 2 cm without the need of post growth machining process for scintillator application. A growth rate of 1 mm/day was achieved along < 011 > direction. The PXRD establishes the phase purity of the grown material. FT-IR and Micro-Raman spectrometers were utilized to justify the presence of the functional groups of the t-stilbene and anisole (solvent). The recorded narrow aromatic vibrations in FT-IR and Raman ascertain the undetectable limit of solvent inclusion in the grown crystal. Absence of new vibrations other than the expected supports the chemical purity of the crystal. The transparency in visible range establishes the suitability of the material for scintillator application where its characteristic emission wavelength under high energy radiation lies. The thermal stability up to 120 degrees C without any structural/phase change was evident from TG/DTA. The radioluminescence spectra were carried out under beta and gamma and found the grown crystal exhibits emissions at 384 and 405 nm which is very similar to the studied photoluminescence characteristics. The scintillation characteristics of the t-stilbene investigated using gamma -rays from various radioactive sources such as Cs-137, Ba-133 and, Cd-109. The scintillation decay time of the grown crystal also studied using the same Cs-133 source and fitted with single exponential component of 12 ns.