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Ba10Zn7M6Q26: Two New Mid-infrared Nonlinear Optical Crystals with T2 Supertetrahedron 3D Framework
摘要： Two new mid-infrared (MIR) nonlinear optical (NLO) chalcogenide crystals, Ba10Zn7In6S26, 1 and Ba10Zn7Ga6Se26, 2 are discovered by traditional solid state reactions. 1 and 2 are isostructural and they represent a novel three-dimensional (3D) framework made by apexe-sharing T2 supertetrahedron 2D layers that are stacked alternately by another kind of T2 supertetrahedra though sharing apexes along the c direction, with T1 tetrahedra inserting in the tunnels and Ba2+ cations locating both in the voids and tunnels. Among them, 1 shows attractive MIR NLO properties of a wide band gap of 3.0 eV, a strong second harmonic generation (SHG) signal about 4.1 times that of the commercial AgGaS2 at particle sizes of 30–46 μm under a 2.05 μm laser radiation, and a high LDT of 37.2 times that of benchmark AgGaS2 at particle sizes of 150–210 μm under a 1.064 μm laser radiation. This distinguishes 1 as a new promising MIR NLO material. In addition, the density functional theory (DFT) analyses suggest that the SHG response of 1 comes mainly from the electronic transitions from S 3p to Ba 5d, Zn 4s, Zn 3d, In 5s, In 5p states.
关键词： chalcogenide,mid-infrared,second harmonic generation,laser damage threshold,nonlinear optical,supertetrahedron
更新于2025-09-04 15:30:14
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A Comparative Study of Vertebrate Corneal Structure: The Evolution of a Refractive Lens
摘要： PURPOSE. Although corneal curvature plays an important role in determining the refractive power of the vertebrate eye, the mechanisms controlling corneal shape remain largely unknown. To address this question, we performed a comparative study of vertebrate corneal structure to identify potential evolutionarily based changes that correlate with the development of a corneal refractive lens. METHODS. Nonlinear optical (NLO) imaging of second-harmonic–generated (SHG) signals was used to image collagen and three-dimensionally reconstruct the lamellar organization in corneas from different vertebrate clades. RESULTS. Second-harmonic–generated images taken normal to the corneal surface showed that corneal collagen in all nonmammalian vertebrates was organized into sheets (?sh and amphibians) or ribbons (reptiles and birds) extending from limbus to limbus that were oriented nearly orthogonal (ranging from 77.78–88.28) to their neighbors. The slight angular offset (28–138) created a rotational pattern that continued throughout the full thickness in ?sh and amphibians and to the very posterior layers in reptiles and birds. Interactions between lamellae were limited to "sutural" ?bers in cartilaginous ?sh, and occasional lamellar branching in ?sh and amphibians. There was a marked increase in lamellar branching in higher vertebrates, such that birds (cid:2) reptiles > amphibians > ?sh. By contrast, mammalian corneas showed a nearly random collagen ?ber organization with no orthogonal, chiral pattern. CONCLUSIONS. Our data indicate that nonmammalian vertebrate corneas share a common orthogonal collagen structural organization that shows increased lamellar branching in higher vertebrate species. Importantly, mammalian corneas showed a different structural organization, suggesting a divergent evolutionary background.
关键词： stroma,nonlinear optical,collagen,cornea,second-harmonic generation
更新于2025-09-04 15:30:14
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Nonlinear optical organic–inorganic crystals: synthesis, structural analysis and verification of harmonic generation in tri-( <i>o</i> -chloroanilinium nitrate)
摘要： The structural and nonlinear optical properties of a new anilinium hybrid crystal of chemical formula (C6H7NCl+NO3?)3 have been investigated. The crystal structure was determined from single-crystal X-ray diffraction measurements performed at a temperature of 100 K which show that the compound crystallizes in a noncentrosymmetric space group (Pna21). The structural analysis was coupled with Hirshfeld surface analysis to evaluate the contribution of the different intermolecular interactions to the formation of supramolecular assemblies in the solid state that exhibit nonlinear optical features. This analysis reveals that the studied compound is characterized by a three-dimensional network of hydrogen bonds and the main contributions are provided by the O···H, C···H, H···H and Cl···H interactions, which alone represent ～85% of the total contributions to the Hirshfeld surfaces. It is noteworthy that the halogen···H contributions are quite comparable with those of the H···H contacts. The nonlinear optical properties were investigated by nonlinear diffuse femtosecond-pulse reflectometry and the obtained results were compared with those of the reference material LiNbO3. The hybrid crystals exhibit notable second (SHG) and third (THG) harmonic generation which confirms its polarity is generated by the different intermolecular interactions. These measurements also highlight that the THG signal of the new anilinium compound normalized to its SHG counterpart is more pronounced than for LiNbO3.
关键词： structural analysis,Hirshfeld surface analysis,intermolecular interactions,nonlinear optical properties
更新于2025-09-04 15:30:14
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Y2(CO3)3?H2O and (NH4)2Ca2Y4(CO3)9?H2O: Partial Aliovalent Cation Substitution Enabling Evolution from Centrosymmetry to Noncentrosymmetry for Nonlinear Optical Response
摘要： An effective approach, the partial aliovalent cation substitution (PACS), was successfully employed to develop nonlinear optical (NLO) material. Two novel rare earth carbonates, Y2(CO3)3·H2O (YC) and (NH4)2Ca2Y4(CO3)9·H2O (CYC), were synthesized, which feature the same honeycomb-like framework structure. From YC to CYC, the partial substitution of Y3+ with Ca2+ led to the evolution of space group from centrosymmetric P63/mcm to noncentrosymmetric P63mc. The CYC exhibited a second harmonic generation (SHG) effect of 2.1 × KH2PO4 (KDP) and a deep-UV cut-off edge (<200 nm). It was concluded that the SHG effect originates from the ordered arrangement of (CO3)2- groups and the dipole polarization enhancement of [Ca0.33Y0.67O9] polyhedra. Specifically, the long-range ordered electric field of channels induced the ordered arrangement of (CO3)2- groups. This synthetic approach and SHG-activated induction mechanism may afford new strategies for the design and synthesis of NLO materials.
关键词： nonlinear optical materials,partial aliovalent cation substitution,rare earth carbonates,deep-UV cut-off edge,second harmonic generation
更新于2025-09-04 15:30:14
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Studies on growth and characterization of (E)-N′-[4-(dimethylamino) benzylidene]-4-hydroxybenzohydrazide hemihydrate: a nonlinear optical material
摘要： Hydrazone compound (E)-N′-[4-(dimethylamino) benzylidene]-4-hydroxybenzohydrazide hemihydrate (DMABHBH) was synthesized and single crystals of DMABHBH were grown by solvent evaporation method at room temperature. Molecular structure of DMABHBH compound was confirmed by 1H and 13C nuclear magnetic resonance techniques. The presence of functional groups was confirmed by Fourier transform infrared and FT Raman spectral analyses. The X-ray crystal structure was elucidated at 173 K by single crystal X-ray diffraction and the results were compared with the corresponding values obtained at 298 K. The compound crystallizes in the chiral monoclinic space group P21. Mechanical stability of the grown crystals was estimated from the Vicker’s microhardness test. Powder second harmonic generation efficiency of DMABHBH is about 1.1 times that of potassium dihydrogen phosphate. DMABHBH is found to show optical limiting behavior at high input light intensities, the third order nonlinear optical absorption coefficient measured using open aperture Z-scan studies, is 0.95 × 10?11 m/W. Anti-bacterial activity was studied using the well and disc diffusion methods.
关键词： X-ray diffraction,Mechanical properties,Nonlinear optical material,Thermal analysis,Antibacterial activity,Hydrazone,Crystal growth
更新于2025-09-04 15:30:14