Vertical bridgman growth and multifaceted optical characterization of high-quality pyrene single crystals for nonlinear optical applications

초록

The high-quality pyrene single crystals were grown by the Vertical Bridgman Technique (VBT). The crystal structure was characterized using single-crystal X-ray diffraction (SCXRD) and powder X-ray diffraction (PXRD) techniques. High-resolution X-ray diffraction (HRXRD) studies of the pyrene single crystals demonstrated superior crystalline quality, with a sharp, symmetric rocking curve and a narrow full width at half maximum (FWHM) of 15.39 arcseconds. Optical transmittance measurements indicated over 85 % transparency in the 500-1100 nm wavelength range, with a lower cut-off at 400 nm. The optical band gap energy was determined to be 3.08 eV. Thermal analysis, including thermogravimetric analysis (TGA) and differential thermal analysis (DTA), revealed a melting point at 154 degrees C and provided insights into the material's decomposition behaviour. Photoluminescence and X-ray induced luminescence were analyzed, and emission peaks were observed at 476 nm, 494 nm, and 498 nm, respectively. The functional groups present in the crystal were identified using Fourier Transform Infrared Spectroscopy (FTIR). Nonlinear optical properties were analyzed via the Z-scan technique, yielding values of 1.040 x 10- 7 esu for the third-order nonlinear susceptibility (chi 3), 2.288 x 10-12 m2/W for the nonlinear refractive index (n2), and 2.517 x 10-4 m/W for the nonlinear absorption coefficient (beta).These findings suggest that pyrene single crystals grown by the Bridgman method have significant potential for applications in nonlinear optics and high-energy (X-ray) detectors.

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