Structure,electronic,and nonlinear optical properties of superalkaline M_(3)O(M=Li,Na)doped cyclo[18]carbon

Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs.In this paper,the geometry,bonding properties,electronic structure,absorption spectrum,and nonlinear optical(NLO)properties of superalkaline M_(3)O(M=Li,Na)-doped cyclo[18]carbon were studied by using density functional theory.M_(3)O and the C_(18) rings are not coplanar.The C_(18) ring still exhibits alternating long and short bonds.The charge transfer between M_(3)O and C_(18) forms stable[M_(3)O]+[C_(18)]-ionic complexes.C_(18)M_(3)O(M=Li,Na)shows striking optical nonlinearity,i.e.,their first-and second-order hyperpolarizability(βvec andγ||)increase considerably atλ=1907 nm and 1460 nm.

Theoretical Investigation on the Second-order Nonlinear Optical Properties of Chiral Amino Acid Zinc(Ⅱ) Porphyrins

Static second-order nonlinear optical effects of amino acid zinc(II) porphyrins 1, 2, 3 and 4 were calculated by the TDHF/PM3 method based on the molecular structures optimized at the semiempirical PM3 quantum chemistry level, showing due to the cancellation of symmetric center, these amino acid zinc(II) porphyrins exhibit second order nonlinear optical response. The analysis of β components indicated that these amino acid zinc(II) porphyrins are of multipola- rizabilities, and they may be ascribed as the “mixture” of octupolar and dipoar molecules with ||βJ=3||/||βJ=1|| ≈ 5. It is found that there are no significant differences between the static β values of non-chiral and chiral amino acid zinc(II) porphyrins. However, the βxyz component, which is quite important to quadratic macroscopic χ (2) susceptibility of chiral material, is increased significantly with the increase of side chain group of amino acids.

Theoretical Investigation on Structures and Second-order Nonlinear Optical Properties of (Thiophene) Manganese Tricarbonyl Cations

The structures of several recently reported organometallic NLO chromophores, (thio-phene) manganese tricarbonyl cations, were fully optimized at the DFT non-local (GGA) level. The calculated results show that the fragments 2-SC4H3CH=CHC6H4-R in these organometallic chromophores are not planar with dihedral angles of 42.2~59.8 between two aromatic rings, which are different from those of uncoordinated counterparts. Based on the DFT geometry opti-mization, the second-order nonlinear optical polarizabilities were calculated by using RPA method. The calculated results indicate that incorporation of +3Mn(CO) unit with thiophene leads to a sub-stantial increase in the second-order polarizability (b).

Synthesis, Structure, and the Second-order Nonlinear Optical Properties of a Borate-carboxylic Acid Compound: KB[L-（-）-C4H4O5]2·H2O

A new organic-inorganic hybrid noncentrosymmetric potassium bis(malic acid)-borates KB(L-(-)-C4H4O5)2·H2O was synthesized by solution method. It was characterized by elemental analysis, FT-IR, TGA and single-crystal X-ray crystallography. It crystallizes in the monoclinic space group P21/c with a = 5.546(6), b = 11.985(13), c = 9.952(11) ?, β = 97.522(17)°, V = 655.8(13) ?3, Z = 2, Dc = 1.682 g/cm3, μ(MoKa) = 0.46 mm–1 and F(000) = 340. 5009 reflections were measured and 2893 independent reflections(Rint = 0.051) were used for further refinement. Single-crystal X-ray diffraction reveals that the complex exhibits a threedimensional pseudo tunnel structure consisting of fundamental building block [B(L-(-)-C4H4O5)2]– anions. The small cavities are occupied by the H2O molecules, which stabilize the whole structure by O–H×××O hydrogen bonds. The complex exhibits nonlinear optical effect as high as 1.5 times that of KDP standard.

An 8-Connected Chiral Lanthanide Metal-organic Framework Constructed from Naturally Camphoric Acid:Crystal Structure,Vibrational Circular Dichroism Spectroscopy and Second-order Nonlinear Optical Effect

A chiral lanthanide metal-organic framework based on enantiopure camphoric acid （D-H2cam）, [Nd3（D-cam）8（H2O）4Cl]n （1）, has been synthesized and characterized by single-crystal X-ray structural analysis, elemental analysis, IR, thermal gravimetric, and X-ray powder diffraction. Crystal data for the title compound are as follows： orthorhombic system, space group P212121 with a = 13.8287（7）, b = 14.0715（7）, c = 25.7403（12） A^°, V = 5008.8（4） A^°3, Mr = 1333.08, Z = 4, F（000） = 2644, Dc = 1.768 g/cm^3, μ（MoKα） = 3.189 mm^-1, the final R = 0.0351 and wR = 0.0814 （I 〉 2σ（I））. Compound 1 displays an 8-connected bcu topology 3D framework and hydrogen-bonding interactions stabilize the solid-state structure. The vibrational circular dichroism （VCD） spectrum and second-order nonlinear optical effect of compound 1 have been studied in the solid state.

Synthesis,Structure and Second-order Nonlinear Optical Activities of a New Tungsten(0) Compound with Pyridine-2-thiolato Ligand,[Et_4N][W(pyS)(CO)_4](pys=C_5H_4NS^-)

The reaction of W（CO）6 with pyOSNa （C5H4NOSNa） and Et4NCl in MeCN affords a new tungsten（0）complex [Et4N][W（pyS）（CO）4] 1 （Mr = 536.29）. The crystal and molecular structures have been determined by X-ray single-crystal diffraction. Complex 1 crystallizes in the orthorhombic system, space group P212121 with α= 8.2429（5）, b = 9.1045（4）, c = 26.8851（14） A, β= 90.00°, V=2017.66（18） A3^, Z = 4, Dc = 1.765 g/cm^3, μ= 58.51 cm^-1, F（000） = 1048, the final R = 0.0204 and wR = 0.0400 for 4432 observed reflections with I 〉 2σ（I）. X-ray structure analysis revealed that the molecule is acentric and has large first=order hyperpolarizability （7.2 × 10^-30 esu）, so it could be an IR second=order nonlinear optical candidate material.

Synthesis of Imidazole Derivatives for Their Second-order Nonlinear Optics

The design and the synthesis of two conjugated donor acceptor imidazole derivatives(1, 2) were carried out for second order nonlinear optics. The thermal properties, the transparency and second order nonlinear optical properties of the molecules were investigated. The experimental results indicate that a good nonlinearity transparency thermal stability trade off is achieved for them.

2D Nb_(2)CT_(x) MXene/MoS_(2) heterostructure construction for nonlinear optical absorption modulation

Two-dimensional(2D)nonlinear optical mediums with high and tunable light modulation capability can significantly stimulate the development of ultrathin,compact,and integrated optoelectronics devices and photonic elements.2D carbides and nitrides of transition metals(MXenes)are a new class of 2D materials with excellent intrinsic and strong light-matter interaction characteristics.However,the current understanding of their photo-physical properties and strategies for improving optical performance is insufficient.To address this issue,we rationally designed and in situ synthesized a 2D Nb_(2)C/MoS_(2) heterostructure that outperforms pristine Nb2C in both linear and nonlinear optical performance.Excellent agreement between experimental and theoretical results demonstrated that the Nb_(2)C/MoS_(2) inherited the preponderance of Nb_(2)C and MoS_(2) in absorption at different wavelengths,resulting in the broadband enhanced optical absorption characteristics.In addition to linear optical modulation,we also achieved stronger near infrared nonlinear optical modulation,with a nonlinear absorption coefficient of Nb_(2)C/MoS_(2) being more than two times that of the pristine Nb_(2)C.These results were supported by the band alinement model which was determined by the X-ray photoelectron spectroscopy(XPS)experiment and first-principal theory calculation.The presented facile synthesis approach and robust light modulation strategy pave the way for broadband optoelectronic devices and optical modulators.

All-optical switching and nonlinear optical properties of HBT in ethanol solution

This paper demonstrates an all-optical switching model system comprising a single pulsed pump beam at 355 nm and a CW He-Ne signal beam at 632.8 nm with 2-（2＇-hydroxyphenyl）benzothiazole （HBT） in ethanol solution. The origins of the optical switching effect were discussed. By the study of nonlinear optical properties for HBT in ethanol solvent, this paper verified that the excited-state intramolecular proton transfer （ESIPT） effect of HBT and the thermal effect of solvent worked on quite different time scales and together induced the change of the refractive index of HBT solution, leading to the signal beam deflection. The results indicated that the HBT molecule could be an excellent candidate for high-speed and high-sensitive optical switching devices.

Synthesis of Poly (3-acetylpyrrolyl methine) with Azobenzene Side Groups and Study on Its Third-order Nonlinear Optical Property

A novel soluble π-conjugated polymer, poly [（3-acetylpyrrole-2, 5-diyl） p-（N, N-dimethylamino） azobenzylidene] （PAPDMAABE）, was synthesized by condensation of 3-acetylpyrrole with 4-aldehyde-4＇-dimethylaminoazobenzene （ADMAA）. The chemical structure of PAPDMAABE was characterized by Fourier transform infrared spectroscopy （FTIR）, ^1H-NMR, and UV-Vis-NIR spectra. Transmission electron microscope （TEM） analysis for PAPDMAABE indicates that part of PAPDMAABE is in crystal state, due to the short-range order of the polymer. Thermogravimetric analysis （TGA） curve shows that the polymer has good thermal stability and its decomposition temperature is 248℃. The optical band gap of PAPDMAABE obtained from the optical absorption spectrum is about 1.73 eV. The resonant third-order nonlinear optical property of PAPDMAABE at 532 nm was studied using degenerate four-wave mixing （DFWM） technique. The resonant third-order nonlinear optical susceptibility of the polymer is about 7.48×10^-8 esu.

Crystal Structure and the Third-order Nonlinear Optical Property of a Cadmium(Ⅱ) Complex Based on a D-π-A Structural Organic Ligand

A triphenylamine-containing Schiff base ligand(L), namely, N-(4-(1 H-imidazol-1-yl)benzylidene)-N,N-diphenylbenzene-1,4-diamine, was synthesized and characterized. By coordination of the ligand with CdI2, a complex CdI2 L2 was obtained. The structure of the complex was analyzed through single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 25.277(5), b = 11.176(5), c = 17.912(5)A,β= 106.056(5)°, V = 4863(3)A3, Z = 4, Dc =1.633 Mg/m3, F(000)= 2360,Μr = 1195.19,μ= 1.766 mm-1, the final R = 0.0323 and wR = 0.0758 for 33414 observed reflections with I > 2?(I). The linear absorption spectra of the complex were experimentally and theoretically studied. And the third-order nonlinear optical(NLO) property of the complex was also measured through Z-scan technique.

New Application of bond Function Basis Sets──ab initio Calculations of Nonlinear Optical Properties

On the basis of adding the bond functions (3s 3p 2d) to the basis sets 6-311G ( 2d 2p ) for increasing the efficiency of the basis sets , we have carried out the MP2 calculations of nonlinear optical properties includintg dipole moment uo,polarizibili- ty ao and hyperpolarizability , for CH4-nFn (n = 1 , 2 , 3). The results are in good a- greement with those of experimentsl The roles of the bond functions in the calcula- tions are shown , i. e., the improved values of the properties are about 2%-7% at the SCF level and about 6%-30% at the correlated level (MP2). It is shown that the more important role of the bond functions in calculating is the im- provement of the effects of the corrections of electronic correlations and the increase of the effects is in the order of. In addition , it is also shown that the cal-, culated value of a property does not change with the bond-function location in our calculations except for the regions close to the nuclei in a molecule.

On the Role of Bond Function in Nonlinear Optical Property Calculations for HF,HCI,LiH,H_2O and NH_3

Dond function basis sets have been used to calculate the molecular nonlinear optical properties which include hyperpolarizability βo , polarizability ao , and dipole moment μo for six molecules. The calculations at the fourth-order Moller-Plesset approximation (MP4) have recovered more than 90% of the experimental values βo , comparecl to that as low as 75% by the other authors. The calculated values of αo and iuo are also in good agreement with those of experiments and superior to that from other work. It is shown that the bond functions improve the calculated results at SCF level and especially at the level of the correction of electronic correlation (MP2 and MP4).

UV-Vis Spectrum and the Third-order Nonlinear Optical Properties of the Chiral Camphorderived β-diketonate Platinum Complexes

UV-Vis spectrum and the third-order nonlinear optical properties of the chiral camphor-derived β-diketonate have been studied at the B3LYP/6-31G＊ level. The results showed that the introduction of electron-drawing group -CF3 and -C3F7 on β-diketonate made the strongest absorption peak red-shift and the lowest energy absorption blue-shied. Introduction of -OC2H5 on the benzene or pyridine ring made the lowest energy absorption blue-shift. When the -C2H3 was introduced on the benzene or pyridine ring, the lowest energy absorption was red-shifted. Introduction of electron-donating group on β-diketonate can enlarge their nonlinear optical properties. On the contrary, the introduction of electron-drawing group dropped it down.

The Third-Order Nonlinear Optical Properties in Cobalt-Doped ZnO Films

We quantitatively investigate the third-order optical nonlinear response of Co-doped ZnO thin films prepared by magnetron sputtering using the Z-scan method. The two-photon absorption and optical Kerr effect are revealed to contribute to the third-order nonlinear response of the Co-doped ZnO films. The nonlinear absorption coefficient β is determined to be approximately 8.8 × 10-5 cm/W and the third-order nonlinear susceptibility X（3） is 2.93 × 10-6 esu. The defect-associated energy levels within the band gap are suggested to be responsible for the enhanced nonlinear response observed in Co-doped ZnO films.

Linear and nonlinear optical properties of Sb-doped GeSe_2 thin films

Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises and the optical band gap decreases from 2.08 eV to 1.41 eV with increasing the Sb content. X-ray photoelectron spectra further confirm the formation of a covalent Sb--Se bond. The third-order nonlinear optical properties of thin films are investigated under femtosecond laser excitation at 800 nm. The results show that the third-order nonlinear optical properties are enhanced with increasing the concentration of Sb. The nonlinear refraction indices of these thin films are measured to be on the order of 10-18 m2/W with a positive sign and the nonlinear absorption coefficients are obtained to be on the order of 10-10 m/W. These excellent properties indicate that Sb-doped Ge-Se films have a good prospect in the applications of nonlinear optical devices.

THIRD ORDER NONLINEAR OPTICAL PROPERTIES OF PERNIGRANILINE SOLUTION IN CONCENTRATED SULFURIC ACID

The fully oxidized state of polyaniline (PANI), pernigraniline (PN), was synthesized by oxidation of the emeraldine base form of PAM dissolved in NMP solvent with m-chloroperoxybenzoic acid. The resulted PN was characterized by FTIR and UV-Visible spectra. The third-order nonlinear optical properties of PN in concentrated sulfuric acid (PN/H2SO4) were measured by a degenerated four wave mixing (DFWM) method. The results obtained suggest that the soliton-pair intermediate state associated with the degenerated state does not play a major role in the third order nonlinear optical properties of PANI.

Optical Waveguide and Nonlinear Properties of Bi_3NdTi_3O_(12) Thin Films

Neodymium-substituted bismuth titanate （Bi3NdTi3O12, BNT） thin films were prepared on quartz substrates by a metal-organic solution deposition process. The crystalline structure was evaluated by X-ray diffraction. Waveguide property was investigated by using prism coupling technique and optical transmittance measurement. The optical nonlinearities of the film were measured by the top-hat Z-scan techniques and a large positive nonlinear refractive index, nonlinear refractive coefficient and two-photon absorption coefficient were determined to be 3.84×10^7 esu, 0.7523 cm^2/GW and 4.81×10^4 cm/GW, respectively. These results reveal that the BNT film may be a kind of new multifunctional materials.

Preparation of Organic Nanoparticle Colloids by Laser Ablation and Their Nonlinear Optical Properties

Suspension of micrometer-sized 1,4-bis（4-methylstyryl）benzene（p-MSB） was converted into colloidal nanocrystal solution by irradiation with an femtosecond laser（800 nm, 1 kHz）. The prepared nanocrystals were rectangular with ca. 100 nm in size. The same crystal structure as that of bulk crystals was confirmed by X-ray diffraction measurement. UV-Vis spectra and emission spectra of the nanoparticle dispersions in dichloromethane（poor solvent） were examined. The nanocrystal exhibits large quantum yield（89%）. The nonlinear optical properties of the nanocrystals were further studied by Z-scan technique with femtosecond laser duration of 120 fs at a wavelength of 800 nm. The results show that the nanocrystals exhibit strong nonlinear absorption.

Crystal Structure,Electrochemical Properties and Third-order Nonlinear Optical Response of 4-Methyloxy benzaldehyde Thiosemicarbazone and Its Copper(Ⅱ)Complex

The crystal structUre of the title ligand and its copper (Ⅱ) complex was determined bysingle crystal X-ray diffraction. The electrochendcal properties and the third-order nonlinearoptical response of the ligand and its copper (Ⅱ) complex were also studied.