Nonlinear studies of Pararosanilin dye in liquid and solid media

Solid-state dye-doped polymers are attractive alternative to the conventional liquid dye solutions. In this paper, nonlinear properties of the dye Pararosanilin has been studied. The third-order nonlinear optical properties of Pararosanilin dye in 1-butanol and dye-doped polymer film were measured by the Z-scan technique using 532 nm diode pumped Nd:Yag laser. This material exhibits negative optical nonlinearity. The dye at 0.4 mM concentration exhibited nonlinear refractive coefficient (n(2) = -6.8 x 10(-8) and -7.11 x 10(-8) (cm(2)/W) in liquid and solid media, respectively), nonlinear absorption coefficient (beta = -7.7 x 10(-4) and -7.93 x 10(-4)cm/W in liquid and solid media, respectively) and susceptibility (chi((3))=3.38 x 10(-6) and 3.53 x 10(-5)esu in liquid and solid media, respectively). These results show that Pararosanilin dye has potential applications in nonlinear optics.     

Investigation of optical nonlinearities of an azo dye using a 532nm diode-pumped Nd:YAG laser

Solid-state dye-doped polymers are attractive alternatives to the conventional liquid dye systems. In this paper, the third order nonlinear optical property of Sudan III, an azo dye in solvents and dye doped polymer films measured using the Z-scan technique is reported. Multiple diffraction rings were observed when the dye doped in both the liquid and solid media was exposed to a diode-pumped Nd:YAG laser at 532nm.     

Integrated wavelength-selective optical waveguides for microfluidic-based laser-induced fluorescence detection

We demonstrate the fabrication and characterization of a novel, inexpensive microchip capable of laser induced fluorescence (LIF) detection using integrated waveguides with built-in optical filters. Integrated wavelength-selective optical waveguides are fabricated by doping poly(dimethysiloxane) (PDMS) with dye molecules. Liquid-core waveguides are created within dye-doped PDMS microfluidic chips by filling channels with high refractive index liquids. Dye molecules are allowed to diffuse into the liquid core from the surrounding dye-doped PDMS. The amount of diffusion is controlled by choosing either polar (low diffusion) or apolar (high diffusion) liquid waveguide cores. The doping dye is chosen to absorb excitation light and to transmit fluorescence emitted by the sample under test. After 24 h, apolar waveguides demonstrate propagation losses of 120 dB cm(-1) (532 nm) and 4.4 dB cm(-1) (633 nm) while polar waveguides experience losses of 8.2 dB cm(-1) (532 nm) and 1.1 dB cm(-1) (633 nm) where 532 and 633 nm light represent the excitation and fluorescence wavelengths, respectively. We demonstrate the separation and detection of end-labelled DNA fragments using polar waveguides for excitation light delivery and apolar waveguides for fluorescence collection. We demonstrate that the dye-doped waveguides can provide performance comparable to a commercial dielectric filter; however, for the present choice of dye, their ultimate performance is limited by autofluorescence from the dye. Through the detection of a BK virus polymerase chain reaction (PCR) product, we demonstrate that the dye-doped PDMS system is an order of magnitude more sensitive than a similar undoped system (SNR: 138 vs. 9) without the use of any external optical filters at the detector.     

Third-order nonlinear optical properties of an ultrathin film containing a porphyrin derivative

An ultrathin nanoscopic multilayer film has been fabricated through the electrostatic layer-by-layer self-assembly of negatively charged 5,10,15,20-tetrakis(3,4,5-trihydroxyphenyl)porphyrin (DHP) and oppositely charged polyethylenimine (PEI). UV-vis spectra showed a continuous and uniform deposition process of PEI and DHP. The film structure was characterized by small-angle X-ray diffraction measurement and AFM images. The nonlinear optical properties of ultrathin film were studied by Z-scan technique with laser duration of 8 ns at a wavelength of 532 nm. The film sample exhibited strong nonlinear saturated absorption and a self-defocusing effect. The nonlinear absorption coefficient and refractive index of the self-assembly ultrathin film are -9.7 x 10(-5) m/W and -7.56 x 10(-12) m(2)/W, respectively.     

Spectral characteristics and nonlinear studies of crystal violet dye

Solid-state dye-doped polymer is an attractive alternative to the conventional liquid dye solution. In this paper, the spectral characteristics and the nonlinear optical properties of the dye crystal violet are studied. The spectral characteristics of crystal violet dye doped poly(methylmethacrylate) modified with additive n-butyl acetate (nBA) are studied by recording its absorption and fluorescence spectra and the results are compared with the corresponding liquid mixture. The nonlinear refractive index of the dye in nBA and dye doped polymer film were measured using z-scan technique, by exciting with He-Ne laser. The results obtained are intercompared. Both the samples of dye crystal violet show a negative nonlinear refractive index. The origin of optical nonlinearity in the dye may be attributed due to laser-heating induced nonlinear effect.     

Optical nonlinear absorption and refraction of CdS and CdS-Ag core-shell quantum dots

The CdS and CdS-Ag core-shell quantum dots (QDs) have been prepared. The nanostructures of the QDs were revealed by transmisson electron microscopy and absorption spectra, respectively. The third-order nonlinear optical properties of the core-shell QDs have been studied by using Z-scan technique with femtosecond pulses at the wavelength of 790 nm. The value of the effective nonlinear absorption coefficient beta(eff) of CdS-Ag QDs is measured to be about 16.8 cm/GW, which is about 400 times larger than that of bare CdS QDs of 3.9 x 10(-2) cm/GW. The nonlinear refraction index gamma of CdS-Ag QDs is about -2.3 x 10(-4) cm(2)GW, which is about 200 times larger than that of bare CdS QDs of 1.0 x 10(-6) cm(2)GW.     

掺杂CuInS2纳米晶玻璃的三阶非线性光学性质

采用溶胶-凝胶法结合气氛控制制备了CuInS2纳米晶玻璃. 利用X射线粉末衍射仪(XRD)和透射电子显微镜(TEM)对CuInS2纳米晶在玻璃中的形貌和微结构进行了表征, 并利用飞秒Z扫描技术对该玻璃的三阶非线性光学性质进行了研究. 结果表明, 在钠硼硅玻璃中形成了尺寸分布为10 nm左右的均一的CuInS2四方晶系纳米晶. 该玻璃体现出优良的三阶非线性光学性能, 其三阶非线性光学折射率γ、吸收系数β和极化率χ(3)分别为8.57×10-16 m2/W, 3.74×10-8 m/W和1.95×10-17 m2/V2.     

Azo-azulene derivatives as second-order nonlinear optical chromophores

The molecular and solid state nonlinear optical (NLO) properties of several (phenylazo)-azulenes are investigated. In particular, (4-nitrophenylazo)-azulene (2b) exhibits a quadratic hyperpolarizability (beta(vec)) of 80 x 10(-30) cm5esu recorded at 1.907 microm by the electric field-induced second-harmonic (EFISH) technique. This molecular material, which crystallizes in the monoclinic noncentrosymmetric space group Pc, exhibits an efficiency 420 times that of urea in second-harmonic generation. The origin of the optical nonlinearity in azo-azulene is discussed in relation with crystal structures and semiempirical calculations within the INDO/SOS formalism, and compared with that of the well known disperse red one (DR1) organic dye.     

六棱柱型金属团簇化合物Mo2Ag4S8(dppy)4的合成与非线性光学性质

新合成了一种六棱柱型金属团簇化合物Mo2Ag4S8(dppy)4, 并用X射线单晶衍射结构分析方法测定了其晶体结构. 应用Z-scan技术研究了该金属团簇化合物在波长为532 nm的纳秒激光脉冲作用下的三阶非线性光学特性. 为了研究Mo2Ag4S8(dppy)4的非线性起源, 应用泵浦探测技术研究了该金属团簇化合物在波长为532 nm的皮秒激光脉冲作用下的光学非线性响应. 实验结果表明金属团簇化合物Mo2Ag4S8(dppy)4具有自聚焦特性和非线性吸收特性; 非线性折射率n2, 非线性吸收系数β和非线性极化率χ(3)分别为1.45×10－10 esu, 6.2×10－10 m/W及2.1×10－11 esu. 实验结果表明金属团簇化合物Mo2Ag4S8(dppy)4的光学非线性响应是非线性吸收和非线性散射共同作用的结果.     

Rhodamine B diffusion in hair as a probe for structural integrity

The aim of this work was to investigate the diffusion of Rhodamine B into bleached, photo bleached and abraded hair, treated or not with an emulsion of ceramide using two different techniques: spectrophotometry and fluorescence optical microscopy with image analysis. This comparison, combined with the Einstein-Smoluchowski equation, allowed validating a methodology that uses the apparent diffusion coefficient of a dye as an index for hair damage. Distinct behaviors of the dye were observed in the cuticle and in the cortex. For a bleached hair sample the apparent diffusion coefficient in the cuticle ranges from 8.2 x 10(-11) cm2 s(-1) to 10 x 10(-11)cm2 s(-1), while for the cortex this value drops to 4.0 x 10(-11) cm2 s(-1) to 4.2 x 10(-11) cm2 s(-1). The diffusion is always faster in the cuticle than in the cortex and the apparent diffusion coefficient shows up to a seven-fold decrease when the dye penetrates the cortex. The chemical, photochemical and physical treatments applied to hair significantly change the values of the apparent diffusion coefficients in the cuticle. The data also proved that the penetration of Rhodamine B into hair occurs via an intercellular path.     

A modified surface forces apparatus for single molecule tracking

To unravel molecular motion within confined liquids, we have combined a surface forces apparatus (SFA) with a highly sensitive fluorescence microscope. Details of our setup including important modifactions to enable the tracking of single dye molecules within nanometer thin confined liquid films are presented. The mechanical and optical performance of our setup is discussed in detail. For a load of 20 mN we observed a circular-shaped contact region (d approximately 300 microm), which results in a confining pressure of about 280 kPa. First experiments on liquid films of tetrakis(2-ethylhexoxy)silane (TEHOS) doped with rhodamine B demonstrated the ability to track single dye molecules within the confining gap of a SFA. The mean diffusion constant was independent of the liquid film thickness of approximately 3x10(-8) cm2/s and thus 10 times smaller than the diffusion constant of rhodamine B in bulk TEHOS. This points to the existence of a thin interface layer with slower molecular dynamics and an attractive potential parallel to the solid surface trapping molecules in this interface region.     

D-π-A-π-D型双查尔酮衍生物的合成和三阶非线性光学性质

合成一种新颖的D-π-A-π-D型双查尔酮衍生物2,6-二[3-(4-甲氧基苯基)]丙烯酰基吡啶,经IR,~1H NMR和HR-MS对其结构进行表征,采用4f相位相干成像技术测定了它的三阶NLO性质并确定了相关参数:脉宽4ns,激光波长450nm,非线性吸收系数β=0.9×10~(-9) m/W,非线性折射率n_2=-0.42×10~(-16) m~2/W,三阶非线性极化率χ~((3))=4.10×10~(-19) m~2/V~2;并测定了紫外光谱和DSC曲线.     

ESR and optical study of Cu2+ doped calcium malonate dihydrate

The ESR study of Cu(2+) doped calcium malonate dihydrate has been done at room temperature. Four magnetically in-equivalent sites for Cu(2+) have been observed. The spin-Hamiltonian parameters evaluated with the fitting of spectra to rhombic symmetry crystalline field are for Cu(2+) site (I): g(x)=2.0963+/-0.0002, g(y)=2.1316+/-0.0002, g(z)=2.4137+/-0.0002, A(x)=(32+/-2)x10(-4)cm(-1), A(y)=(34+/-2)x10(-4)cm(-1), A(z)=(49+/-2)x10(-4)cm(-1), for site (II): g(x)=2.0668+/-0.0002, g(y)=2.0800+/-0.0002, g(z)=2.3561+/-0.0002, A(x)=(34+/-2)x10(-4)cm(-1), A(y)=(36+/-2)x10(-4)cm(-1), A(z)=(51+/-2)x10(-4)cm(-1), for site (III): g(x)=2.0438+/-0.0002, g(y)=2.0623+/-0.0002, g(z)=2.2821+/-0.0002, A(x)=(34+/-2)x10(-4)cm(-1), A(y)=(36+/-2)x10(-4)cm(-1), A(z)=(53+/-2)x10(-4)cm(-1), and for site (IV): g(x)=2.0063+/-0.0002, g(y)=2.0241+/-0.0002, g(z)=2.2357+/-0.0002, A(x)=(35+/-2)x10(-4)cm(-1), A(y)=(37+/-2)x10(-4)cm(-1), A(z)=(54+/-2)x10(-4)cm(-1). The ground state wave function of Cu(2+) has also been determined. The g-anisotropy has been estimated and compared with the experimental value. Further with the help of optical study the nature of bonding of metal ion with different ligands in the complex has been discussed.     

Lateral diffusion coefficients of an eicosanyl-based bisglycerophosphocholine determined by PFG-NMR and FRAP

We report the lateral diffusion properties of 2,2'-di-O-decyl-3,3'-di-O-(eicosanyl)-bis-(rac-glycero)-1,1'-diphosphocholine (C20BAS) using pulsed-field gradient NMR (PFG-NMR) and fluorescence recovery after photobleaching (FRAP). C20BAS membranes display a melting transition at Tm = 15.7 degrees C, as determined by differential scanning calorimetry and 31P NMR chemical shift anisotropy. The lateral diffusion coefficient of C20BAS, as determined by PFG-NMR and FRAP, at 25 degrees C, were DPFG-NMR = 1.9 +/- 0.6 x 10(-8) cm2/s and DFRAP C20BAS = 1.2 +/- 0.1 x 10(-8) cm2/s, respectively. In comparison, the lateral diffusion coefficient of the monopolar phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), was 1.8 +/- 0.9 x 10(-8) and 2.5 +/- 0.9 x 10(-8) cm2/s using PFG-NMR and FRAP, respectively.     

Proton dynamics in lithium-ammonia solutions and expanded metals

Quasielastic neutron scattering has been used to study proton dynamics in the system lithium-ammonia at concentrations of 0, 4, 12, and 20 mole percent metal (MPM) in both the liquid and solid (expanded metal) phases. At 230 K, in the homogenous liquid state, we find that the proton self-diffusion coefficient first increases with metal concentration, from 5.6x10(-5) cm2 s(-1) in pure ammonia to 7.8x10(-5) cm2 s(-1) at 12 MPM. At higher concentrations we note a small decrease to a value of 7.0x10(-5) cm2 s(-1) at 20 MPM (saturation). These results are consistent with NMR data, and can be explained in terms of the competing influences of the electron and ion solvation. At saturation, the solution freezes to form a series of expanded metal compounds of composition Li(NH3)4. Above the melting point, at 100 K, we are able to fit our data to a jump-diffusion model, with a mean jump length (l) of 2.1 A and residence time (tau) of 3.1 ps. This model gives a diffusion coefficient of 2.3x10(-5) cm2 s(-1). In solid phase I (cubic, stable from 88.8 to 82.2 K) we find that the protons are still undergoing this jump diffusion, with l=2.0 A and tau=3.9 ps giving a diffusion coefficient of 1.8x10(-5) cm2 s(-1). Such motion gives way to purely localized rotation in solid phases IIa (from 82.2 to 69 K) and IIb (stable from 69 to 25 K). We find rotational correlation times (tau(rot)) of the order of 2.0 and 7.3 ps in phases IIa and IIb, respectively. These values can be compared with a rotational mode in solid ammonia with tau(rot) approximately 2.4 ps at 150 K.     

2-(芘-1-基)-1,8-萘啶的合成、理论计算及超快三阶非线性光学响应

合成了一个供体-受体(D-A)型含芘萘啶衍生物2-(芘-1-基)-1,8-萘啶(PN)。 通过核磁共振波谱(NMR)、傅里叶变换红外光谱(FTIR)、液-质联用仪(LC-MS)表征了其结构。 通过电子光谱和Z-扫描技术方法分别研究了化合物PN的线性光学性质和三阶非线性光学吸收,采用综合热分析方法测定了它的热稳定性。 结果表明,在532 nm、180 fs条件下,PN的三阶非线性吸收行为为反饱和吸收,其吸收系数为β=9.0×10^-14 m/W,显示出超快三阶非线性光学响应。 运用密度泛函理论方法计算了分子轨道能量、极化率和超极化率,结果表明电子转移能够在分子内部进行。 2-(芘-1-基)-1,8-萘啶的紫外光谱在450 nm以上无吸收,在非线性光学吸收、激光防护、吸收型光开关或双稳器件等方面可作备选材料。     

Synthesis, structure, and large optical limiting effect of the first coordination polymeric cluster based on an {I@[AgI(inh)]6} hexagram block

In this paper, treatment of N-(isonicotinoyl)-N'-nicotinoylhydrazine (inh) and AgI with excess KI afforded a unique coordination polymeric cluster {[AgI(inh)]6(KI)}n (1) with the hexagram cluster units centered by mu6-I. In the polymer these hexagram units are parallel to the ab plane and are linked by separated K+ centers through inh. Polymer 1 represents the first example of coinstantaneous cation-anion-induced supramolecular self-assembly with nanoscale inner cavities. The polymer's third-order nonlinear optical (NLO) properties were determined by the Z-scan technique in DMF solution. The results show that the polymer has strong third-order optical nonlinearities. The nonlinear absorptive index a2 and refractive index n2 are calculated to be 1.044 x 10(-9) mW(-1) and 2.827 x 10(-11) esu, respectively. The values are comparable to those of the reported cluster polymers. The optical limiting experiments show that the present cluster exhibits a large optical limiting capacity. The value of the limiting threshold was measured as 0.53 J cm(-2) from the optical limiting experimental data. This value is three times better than 1.6 J cm(-2) of C60. This paper also gives a summary and comparison on the optical limiting properties of oligomeric and polymeric clusters.     

EPR and optical absorption studies on VO2+ ions in L-asparagine monohydrate single crystals

X-Band electron paramagnetic resonance (EPR) studies of VO(2+) ions in l-asparagine monohydrate single crystals have been done at room temperature. Detailed EPR analysis indicates the presence of two magnetically inequivalent VO(2+) sites. Both the vanadyl complexes are found to take up interstitial position. The angular variation of the EPR spectra in three planes ab, bc and ca are used to determine principal g and A tensors. For the two sites the spin Hamiltonian parameters are, site I: g(x)=1.9633, g(y)=2.0274, g(z)=1.9797, A(x)=88, A(y)=61, A(z)=161x10(-4)cm(-1); site II: g(x)=1.9627, g(y)=1.9880, g(z)=1.9425, A(x)=90, A(y)=66, A(z)=167x10(-4)cm(-1). The optical absorption study is also carried out at room temperature and absorption bands are assigned to various transitions. The theoretical band positions are obtained using energy expressions and a good agreement is found with the experimental values. By correlating EPR and optical data different molecular orbital coefficients are evaluated and the nature of bonding in the crystal is discussed.     

Synthesis, linear, and quadratic-nonlinear optical properties of octupolar D3 and D2d bipyridyl metal complexes

A series of D3 (Fe(II), Ru(II), Zn(II), Hg(II)) and D2d (Cu(I), Ag(I), Zn(II)) octupolar metal complexes featuring different functionalized bipyridyl ligands has been synthesized, and their thermal, linear (absorption and emission), and nonlinear optical (NLO) properties were determined. Their quadratic NLO susceptibilities were determined by harmonic light scattering at 1.91 microm, and the molecular hyperpolarizability (beta0) values are in the range of 200-657 x 10(-30) esu for octahedral complexes and 70-157 x 10(-30) esu for tetrahedral complexes. The octahedral zinc(II) complex 1 e, which contains a 4,4'-oligophenylenevinylene-functionalized 2,2'-bipyridine, exhibits the highest quadratic hyperpolarizability ever reported for an octupolar derivative (lambdamax=482 nm, beta1.91(1 e)=870 x 10(-30) esu, beta0(1 e)=657 x 10(-30) esu). Herein, we demonstrate that the optical and nonlinear optical (NLO) properties are strongly influenced by the symmetry of the complexes, the nature of the ligands (donor endgroups and pi linkers), and the nature of the metallic centers. For example, the length of the pi-conjugated backbone, the Lewis acidity of the metal ion, and the increase of ligand-to-metal ratio result in a substantial enhancement of beta. The contribution of the metal-to-ligand (MLCT) transition to the molecular hyperpolarizability is also discussed with respect to octahedral d6 complexes (M=Fe, Ru).     

Fabrication of ultrathin films with large third-order nonlinear optical properties.

An ultrathin composite film containing anionic Ag-His complexes (His: L-Histidine) and oppositely charged BH-PPV was fabricated by means of the electrostatic layer-by-layer self-assembly technique. UV/Vis spectra showed a continuous deposition process of Ag-His complexes and BH-PPV. The film structure was characterized by using small-angle X-ray diffraction, AFM, and SEM. The nonlinear optical properties of the ultrathin film were studied by using the Z-scan technique with a laser duration of 8 ns at a wavelength of 532 nm. The film sample exhibited a strong nonlinear saturated absorption, with an alpha2 value of -3.9 x 10(-5) mW(-1) and a self-defocusing effect with an n2 value of -4.78 x 10 (-12) m2W(-1).