Chalcones as third order NLO material...

What is it about?

Third order nonlinear material of 4-[(1 E)-3-(5-chlorothiophen-2-yl)-3-oxoprop-1-en-1-yl]phenyl4-methylbenzene-1-sulfonate (4 TP MS) was synthesized by Claisen Schmidt condensation reaction method and single crystals were grown by slow evaporation technique. The functional groups corresponding to the vibrational frequencies has been confirmed through FT-IR and FT-RAMAN spectroscopic techniques. The single crystal XRD analysis revealed the crystal is belonging to monoclinic crystal structure with P21/n space group. The optical properties were studied by UV-VIS spectroscopy and photoluminescence spectroscopy. The cut-off wavelength of 4 TPMS is found to be 432 nm and the crystal is transparent in entire visible and near IR region. Using absorbance data, the parameters like extinction co-efficient, reflectance, electrical conductivity, optical conductivity, complex dielectric constant, lattice dielectric constant and ratio of carrier concentration to effective mass has been analyzed. The crystal has blue light emission property with less defects were observed from photoluminescence studies. The 4 TPMS is thermally stable up to 254 °C. The dielectric properties like dielectric constant and dielectric loss were studied. The low value dielectric loss at high frequency region enhances the optical quality of the material. The third order nonlinear properties of nonlinear absorption and nonlinear refraction were studied through open/closed aperture Z-Scan technique. The high value nonlinear absorption co-efficient of 4 TPMS makes the material suitable for optical limiting application. These optical limiting properties were extracted from open aperture Z-Scan data and this behavior is due to reverse saturable absorption. The large value of third order nonlinear susceptibility is of the order of 10−11 esu and material has better capability to be used optical device applications.

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Why is it important?

These type of compounds have potential applications in optics. Summary of our findings are: The novel chalcone derivative of 4 TPMS was synthesized and single crystals were grown by solvent evaporation technique. The vibrational and functional groups have been identified from FT-IR and FT-RAMAN spectroscopic investigations. The single crystal XRD studies revealed monoclinic structure h aving P21/n space group. The molecule is interesting due to the presence of tosyloxy group as aldehyde and thiophene ring as ketone, which can easily be replaced by nucleophile. The material is transparent in visible and near IR region with cut off wavelength of 432 nm. The direct energy band gap has been confirmed through theoretical aspects. The 4 TPMS is thermally stable up to 254 °C and melting point of the crystal is found to be 115 °C. PL studies revealed that defects are responsible for blue light emission. This feature can be used for blue LED applications. The low dielectric constant and the low dielectric loss factor at higher frequency regions enhances the optical quality of the material with lesser imperfections. The material shows high nonlinear absorption co-efficient value of 5.52 cm/GW at input intensity of 2.39 GW/cm2. The nonlinear refractive index and nonlinear susceptibility obtained in the order of 10−11 esu which is very much greater than that of some reported chalcone derivatives. It is to be noted that reverse saturable absorption is responsible for optical limiting effect and hence this material is useful for optical limiting applications.

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