Large third-order nonlinear susceptibility of newly synthesized 3-amino-1H-1,2,4-triazolium p-toluene sulfonate (TPTSA) single crystal measured by the open and closed aperture of the Z-scan technique

Abstract

The researchers employed the Slow Evaporation Solution Technique (SEST) to grow a third-order nonlinear optical 3-amino-1H-1,2,4-triazolium p-toluene sulfonate (TPTSA) crystal and subsequently conducted an X-ray structural examination. The resulting solution's monoclinic structure (P21/c space group) was confirmed and refined using the SHELXS 2018/3 program, and this marks the first instance of a TPTSA single-crystal structure being reported. To further investigate the optical qualities of the TPTSA crystals, including reflectance (R), bandgap (Eg), refractive index (n), and extinction coefficient (K), we utilized a UV–Vis–NIR spectrophotometer, which demonstrated a transmittance of 82%. Moreover, photoluminescence spectrum analysis revealed that the crystal emits light at 294 and 471 nm. Thermal properties of the TPTSA single crystals were also studied, and it was determined that TPTSA remains stable up to 197 °C. A Hirshfeld surface study showed various inter and intra molecular interactions within the TPTSA compound. Based on the crystal's Z-scan parameters, such as absorption coefficient (β = 1.02412 × 10−4 m/W), nonlinear refractive index (n2 = 9.7348 × 10−12 m2/W), and third-order linear optical susceptibility (χ3) of TPTSA, which was found to be 3 × 10−8 esu, it is evident that the nonlinear properties of this crystal make it suitable for third harmonic generation applications. The comprehensive structural analysis and physical characteristics of the TPTSA crystal demonstrate its potential for applications in harmonic generation.