Effect of concentration and particle size on nonlinearity of Au nano-fluid prepared by γ (Co) radiation

Nonlinear properties of Au nano-fluid prepared by γ-radiation method at different concentrations were investigated. Measurements of nonlinear refractive index and nonlinear absorption coefficient were carried out using a single beam Z-scan technique. A green CW laser beam operated at 532 nm was used as excitation source. The Au nano-fluid shows a good third order nonlinear response. The sign of the nonlinear refractive index is found to be negative and the magnitude is in the order of 10⁻⁷ cm²/W. This nonlinear effect increases as the concentration increases from 3.119 × 10⁻⁴ to 2.354 × 10⁻³ M which correspond to particle sizes of 4.0-30.5 nm, respectively. A good linear relationship was obtained between nonlinear refractive index and concentration. However the relationship between nonlinear refractive index and particle size was nonlinear behavior.     

新型金属团簇化合物的光限幅特性研究

应用倍频 Nd:YAG脉冲激光 ,在波长为 5 32 nm、脉冲宽度为 8ns的条件下 ,研究了金属团簇化合物WOS3Cu3I(2 - Me Py) 3的光限幅特性。其光限福特性优于富勒烯。Z- Scan研究结果表明 :该团簇具有自聚焦特性 ,其光限幅起源于激发态吸收     

Computational,structural, spectral,optical and Hirshfeld surface analysis of (E)-2-(3,4,5-trimethoxybenzylidene) hydrazinecarbothioamide (ETMBHC): Third order NLO single crystal

By using a slow evaporation solution growth technique, single crystals of (E)-2-(3,4,5-trimethoxybenzylidene) hydrazine carbothioamide (ETMBHC) have been produced. The crystalline compound has the following properties: a = 7.471 (3), b = 9.705 (4), c = 11.168 (4), = 73.200(11)°, = 70.633 (10)°, = 70.334 (10)°; it belongs to the triclinic system with space group P. The ETMBHC chemical is a member of the P-1 triclinic system. Fourier transformations and Fourier transform infrared (FT-IR) The functional groups have been identified by Raman spectrum research. To understand how charge transfer occurs inside molecules and to establish that the title crystal is appropriate for NLO applications, the HOMO and LUMO energies for the grown crystal were computed. TGA-DTG analysis was used to study the melting point and thermal stability. Z-scan analyses were used to determine the grown crystal's nonlinear absorption coefficient and third-order nonlinear refractive index.     

Third-order Optical Nonlinearities of a Series of Compounds Derived from a Keplerate Type Molybdenum-oxide-based Polyoxometalate

Abstract By reacting the unique Keplerate type molybdenum-oxide based polyoxometalate （NH4）42·[MoI320372·（CH3COO）30（H2O）y2]·ca.300H2·ca. 10CH3COONH4（1） with tetramethylammonium bromide, a new derivative （NH4）26[TMA]16{MoI32O372（H2O）72（CH3COO）30}·ca.7NH4CH3COO·ca.189H2O（2, TMA=tetramethylammonium） was prepared. Compound 2 was characterized by Fourier transform infrared spectroscopy（FTIR）, UV-Vis, elemental and thermogravimetric analyses. By the well-established Z-scan technique, investigations on the nonlinear opti- cal（NLO） properties of the series of compounds derived from the Keplerate type molybdenum-oxide-based poly- oxometalate, namely, the newly prepared compound 2, the three previously reported compounds, included compound 1, （NH4hs（TBA）24{Mo132O372（H2O）72（CH3COO）30}·ca.7NH4CH3COO·ca. 173H2O（3, TBA=tetrabutylammonium） and （DODA）40（NH4）2[（H2O）nMo132O372（CH3COO）3o（H20）72]（4, DODA=dimethyldioctadecylammonium）, reveal that the third-order nonlinearity[x（3）] values of compounds 1, 2 and 3 in the DMF/H2O solution and compound 4 in chloro- form are almost the same, which indicates that the counter cations with different length of alkyl chains show ignora- ble impacts on the NLO susceptibility. In other words, the remarkable third-order nonlinearities[x（3）≈10 19 m2/V2] mainly come from the [MoI32O372（CH3COO）30（H2O）72]42 anions. This fact reveals that the applications of the NLO active polyoxometalates in various environments（such as hydrophilic, hydrophobic, polar, apolar, etc.） can be achieved by simply varying cations to meet the demands in the design of diverse devices. Keywords Keplerate type polyoxometalate; Nonlinear optical property; Z-Scan technique; Self-defocusing; Reverse saturable absorption     

Evaluation of nonlinear optical parameters of TiN/PVA nanocomposite – A comparison between semi empirical relation and Z-Scan results

We report on the third order non linearity of TiN/PVA nanocomposites. Linear and nonlinear optical properties were studied from theoretical and experimental method. Theoretical method involved Tichy and Ticha relation pooled with generalised Miller's rule. During the study dispersion of refractive index is analysed using the Wemple–Di Domenico single oscillator model. Z-Scan was used as the experimental tool. The results derived from theoretical method deviated greatly from the experimental. We believe that such incongruity is due to the SPR property of the TiN nanoparticle whose SPR peak almost coincides with the irradiated laser wavelength.     

Crystal growth,structural, spectral,optical, DFT analysis and Z-scan analysis of pyridine-1-ium-2-carboxylatehydrogenbromide (PHBr) for optoelectronic and nonlinear optical applications

A single crystal of Pyridine-1-ium-2-carboxylatehydrogenbromide (PHBr) was grown using the Slow Evaporation Solution Technique. Using Single Crystal X-Ray Diffraction analysis, the crystal lattice characteristics and molecular structure of the grown crystal of PHBr were found and it corresponds to the Triclinic crystal system with space group Pī. Intra and intermolecular interactions were visualized using Hirshfeld surface analysis. The theoretical calculation conducted by Density Functional Theory (DFT) and it is well agreed with the experimental results. The Molecular optimized geometry, FT-IR and HOMO-LUMO energy gap were computed using the B3LYP level of theory with a 6-31 + G (d,p) basis set. The FT-IR spectrum studies are given here to look at the modes of vibration of numerous functional groups found in the PHBr crystal. The measurements of UV–visible NIR transmittance show that the crystal has a high transmittance over the whole visible spectrum. The Z-scan approach is used to perform third-order nonlinear optical (NLO) investigations on a PHBr crystal and optical properties such as linear and nonlinear refractive index are computed.     

CuInS2纳米晶的结构、形貌与光学性能研究

采用A-Pot法, 以乙酰丙酮铜[Cu(acac)₂]为铜源, 硬脂酸铟[In(St)₃]为铟源, 正十二硫醇(DDT)为硫源和稳定剂, 1-十八烯(ODE)为溶剂, 在250 ℃条件下, 反应50 min, 合成了CuInS₂粉体. 用X射线粉末衍射仪(XRD)、透射电子显微镜(TEM)、能量分散光谱仪(EDS)、X射线光电子能谱(XPS)等对粉体的结构、形貌、相组成进行表征. 结果表明: 产物为四角晶系的黄铜矿结构, 棒状CuInS₂纳米晶的直径为2 nm, 长约70 nm. 通过Z-Scan技术对分散在正己烷中CuInS₂纳米棒的三阶光学非线性进行测试, 在入射波长为770 nm的条件下, 得出三阶光学非线性折射率γ、三阶光学非线性吸收系数β以及三阶光学非线性极化率χ⁽³⁾分别为1.76×10^－17 m²/W, 7.95×10^－11 m/W和8.60×10^－12 esu.