双核磺化酞菁钴在混合溶液中聚集现象的光谱和电化学研究

用光谱法研究了双核磺化酞菁钴(bi-CoPc)在水溶液中的聚集现象,讨论了各种有机溶剂与水按不同体积比形成的混合溶液对其解聚的作用,以及pH值对bi-CoPc聚集的影响。用透射电子显微镜观察了bi-CoPc在水溶液及30％丙醇-水混合溶液中的形貌。研究了bi-CoPc在混合溶液中的电化学行为。     

Influence of C60 Aggregation on Pseudorotation in the Excited Triplet State Probed by Multifrequency Time-Resolved EPR

The influence of C₆₀ aggregation on time-resolved (TR) electron paramagnetic resonance (EPR) of C₆₀ in the excited triplet state was investigated by multifrequency EPR techniques. Temperature-independent X-band (9.7 GHz) TR-EPR spectra were observed in a fresh toluene solution, while temperature-dependent ones were reported in literatures. The experimental spectra in this study indicated that the pseudorotation of pristine C₆₀ in frozen toluene solution is not frozen out even at lower temperatures. Careful investigations of TR-EPR and its decay kinetics demonstrated that the pseudorotation can be affected by C₆₀ aggregation. A comparison between X- and W-band (94.9 GHz) results indicated that the aggregation can be accelerated by a capillary effect. Three decay constants were extracted from the analysis of the decay kinetics. The fastest component was ascribed to the pseudorotation, which was independent of temperature in the range of 10–40 K. The temperature dependences of the decay kinetics showed that the pseudorotation is not affected by C₆₀ aggregation at higher temperatures.     

Characteristics of the capillary motions of surfactant solutions with a charged free surface

Abastract A dispersion relation is derived and analyzed for the spectrum of capillary motions on the charged plane surface of a liquid in which a surfactant is dissolved. It is shown that two additional wave motions are generated in this kind of system by bulk diffusion and surface diffusion of the surfactant and are sensitive to the diffusion coefficients and elastic properties of the surfactant films and to the viscosity of the solution and the presence of a surface charge. In solutions of inactive surfactants the growth rate of Tonks-Frenkel instability increases as the surfactant concentration increases. Zh. Tekh. Fiz. 68, 22–29 (February 1998)     

Form-factors for different aggregation models of micelles

Spherical micelles in ionic micellar solutions, often aggregate to form spherical, cylindrical or chain-like aggregates on addition of salt to the solution. It is known that the technique of small angle neutron scattering (SANS) can be used to distinguish spherical and cylindrical aggregates. To examine if SANS can be used to distinguish the latter two aggregation processes, we have calculated the angular distribution of scattered neutrons from 0.002 M CTAB solutions. These calculations show that aggregation of CTAB micelles results in large changes in SANS spectra. The shapes of SANS spectra are different for the above three types of aggregates, suggesting that technique of SANS can indeed be used to distinguish the three aggregation processes. The size of the aggregate can also be obtained from such studies.     

中草药猫人参与其同科同属植物的光谱分析与鉴别

本文用紫外光谱和荧光光谱等方法对猫人参与其同科同属的木天蓼、藤梨根进行了分析与鉴别。结果表明 :在 2 54nm紫外灯下 ,猫人参水溶液几无荧光 ,而木天蓼、藤梨根水溶液均显较强荧光 ;三种药材提取液的紫外光谱和荧光光谱存在明显差别。     

Observation of sharp resonances in the spontaneous Raman spectrum of a single optically levitated microdroplet

Sharp resonances have been observed in the spontaneous Raman spectra of single, optically levitated microdroplets. The droplets, 10 to 35 μm in diameter, were suspended by a CW argon laser beam which also served as the Raman excitation source. Experiments with dioctyl phthalate (DOP) and silicone oil confirmed that all Raman bands present in the bulk liquid spectra were also observable in the levitated droplet spectra, in agreement with previous micro-Raman studies of droplets on substrates. However, superimposed on the spectra of the levitated droplets was a series of sharp features not present in the bulk liquid spectra. Time-resolved experiments with growing DOP droplets showed that the sharp Raman features have the same origin as the elastic light scattering and flourescence resonances observed in previous studies of microspheres and fibers.     

Excimer Emission of Acridine Orange Adsorbed on Gadolinium-Yttrium Orthovanadate Nanoparticles

Studying the complexes of inorganic nanoparticles – organic dye molecules is of great importance for their theranostics application. In this paper, we report gadolinium-yttrium orthovanadate nanoparticles (VNPs) – Acridine Orange (AO) complex formation in water solutions. To study the interactions between VNPs and AO, the methods of steady-state and time-resolved spectroscopy were used. It was shown that in aqueous solutions containing VNPs, AO aggregation takes place with a sandwich-like stacking of AO molecules in the near-surface layer of VNPs. The VNPs–AO complex formation causes significant changes in the AO fluorescence spectrum, namely, the appearance of a new broad, structureless band in the long-wavelength spectral edge, which was not observed in AO spectrum in a pure water solution. By analyzing of the absorption, fluorescence excitation spectra and fluorescence decay, the static excimer origin of the long-wavelength fluorescence band has been established.     

Triple-quantum-filtered (23)Na NMR spectroscopy of subcutaneously implanted 9l gliosarcoma in the rat in the presence of TmDOTP(5-1)

The utility of triple-quantum (TQ)-filtered (23)Na NMR spectroscopy for discriminating between intra- and extracellular Na(+)(Na(i)(+) and Na(e)(+), respectively) in a solid tumor in vivo was evaluated using TmDOTP(5-) as a (23)Na shift reagent. Infusion of 80 mM TmDOTP(5-) without added Ca(2+) produced baseline-resolved Na(i)(+) and Na(e)(+) peaks in both single-quantum (SQ) and TQ-filtered (23)Na spectra. The Na(i)(+) signal represented 22+/-4% of the SQ spectrum, but 59+/-10% of the TQ-filtered spectrum. Therefore, the Na(i)(+) contribution in TQ-filtered spectra is much higher than in SQ spectra. Both SQ and TQ-filtered Na(i)(+) signals increased by about 75% 1 h after sacrificing the animal. The TQ-filtered relaxation times did not change during this time, indicating that changes observed in TQ-filtered spectra collected with a preparation time of 3 ms represent changes in the concentration of sodium ions contributing to the TQ-filtered signal. Similar experiments were conducted without TmDOTP(5-) to determine changes in the Na(e)(+) signal in the absence of the shift reagent. The changes in total SQ and TQ-filtered signals 1 h after sacrificing the animal showed that the SQ Na(e)(+) signal decreased by approximately 35%, while the TQ-filtered Na(e)(+) signal did not change significantly. This demonstrates that the TQ-filtered (23)Na signal is relatively insensitive to changes in Na(e)(+) content. To our knowledge, this work represents the first evaluation of multiple-quantum-filtered (23)Na spectroscopy to discriminate between intra- and extracellular Na(+) in a solid tumor in vivo.     

Structural transformations and phase transitions in aqueous solutions of gadolinium nitrate in the course of freezing

The microstructure of Gd(NO₃)₃ aqueous solutions in the course of cooling at different rates is investigated using electron paramagnetic resonance. The local concentrations of Gd³⁺ ions in microregions are estimated, the concentration boundary at which the solution is completely vitrified throughout its volume is revealed, and the temperature of vitrification of liquid microregions (eutectic temperature) and the eutectic composition are determined. It is found that the adsorption of Gd³⁺ aqua ions on the capillary surface affects the crystallization of water and the process of concentration of the solute. It is demonstrated that the anomalous experimental dependence δH(C₀), which is observed for vitrified water-glycerol solutions with a uniform distribution of paramagnetic centers over the sample, agrees well with the theoretical curve in the case when allowances are made not only for the dipole-dipole interactions but also for the inhomogeneous broadening of the EPR lines in the spectra with an incompletely resolved fine structure.     

磺化金属萘酞菁聚集倾向的光谱研究

在磺化金属萘酞菁的荧光光谱和电子吸收光谱的Q谱带上观察到激基缔合物的荧光光谱峰和基态聚集物的吸收光谱峰。荧光光谱和吸收光谱实验说明 ,溶液中聚体分子和单体分子同时存在 ;聚体放出或吸收光子后都解离为单体 ;在荧光光谱中金属萘酞菁的激基缔合物荧光峰相对于单体荧光峰发生红移 ,在吸收光谱中金属萘酞菁基态聚集体的吸收峰相对于单体吸收峰发生蓝移 ,聚集体的荧光光谱和吸收光谱有镜像对称关系。磺化萘酞菁钴浓度较大时 ,其荧光光谱的猝灭较大。     

Stabilization and acoustic spectra of a cavitation cluster in an ultrasonic spherical cavity

The dynamics, stabilization, and acoustic spectra of a bubble cluster in different liquids are investigated under the condition of ultrasonic cavitation. Experimental data for the dynamics of a spherical ultrasonic cluster near the end face of a rod, capillary, or pressure sensor placed in the antinode of a pressure standing wave at the center of a single-wave spherical piezoelectric concentrator (piezoelectric sphere) are presented. The variation of the cluster size with the parameters of the ultrasonic field and properties of the liquid is studied. It is found that the shape, collapse dynamics, and stability of the cavitation cluster have a significant influence on the acoustocapillary effect. It is shown that the maximal acoustocapillary effect and sonoluminescence are observed when a stable cluster with spherically symmetric collapse dynamics is provided at the end of a capillary in a 50% solution of glycerol. Using a small-size piezotransducer placed at the center of the sphere, the acoustic pressure is measured and acoustic spectra are studied for different voltages across the piezosphere and during the formation of variously shaped cavitation clusters. In the case of fully developed cavitation and a spherical cluster, the acoustic spectra contain subharmonic components, the cavitation noise factor rises to 35%, and the maximum of the noise envelope shifts toward higher frequencies.     

Self-aggregates formation of tetrachloroperylene acid esters in Langmuir and Langmuir-Blodgett films

Using Langmuir and Langmuir-Blodgett techniques molecular films of chlorinated perylene derivatives, namely tetra-n-butyl-1,6,7,12-tetrachloroperylene-3,4,9,10-tetracarboxylate (PCn for n = 1, 5, 9) have been studied. The Langmuir films of pure compounds and mixed with liquid crystalline 4-octyl-4′-cyanobiphenyl (8CB) were characterized by surface pressure-mean molecular area isotherms. An additive rule reveals miscibility of all the dyes with 8CB but shows different types of intermolecular interaction forces. The pure and mixed Langmuir films were transferred onto quartz plates and characterized spectroscopically. Absorption and fluorescence spectra were recorded for the samples in form of diluted chloroform solution, the dye with 8CB mixtures in monomolecular Langmuir-Blodgett films and in liquid crystal cells. Different tendency to aggregation of the dye with short and long alkyl chains was observed. It is shown that the dye molecule stacking and aggregation of the chlorinated perylene dyes depend on the dye concentration and are related to the torsion of the perylene core.     

Isotope effects in the Lyman and Werner systems of molecular hydrogen

A prototype model of amphiphilic discotic binary solutions is proposed, and its statistical mechanics investigated by Monte Carlo computer simulation procedures. Data are presented from a large number of simulations, over 50 separate systems in all, carried out at a single relatively low pressure but covering almost the entire temperature-composition range of phase space beyond the melting line, including successful simulations of equilibrated cluster distributions throughout the isotropic solution phase. These data are in agreement with the well known theory of linear aggregation, but a major surprise is found in that the associated equilibrium constant possesses a strong concentration dependence at low temperature. The global aggregation behaviour is described in detail and discussed in the context of the standard state that is usually invoked when applying linear aggregation theory to experimental systems. It is concluded that as the temperature decreases the ideal behaviour of these cluster distribution data shows more and more influence from the nearby infinite polydispersity limit. At sufficiently high surfactant concentration our model discotic solutions melt first into partially ordered states of aligned aggregates (columns of discs) surrounded by liquid solvent. Both a nematic phase and a hexagonally ordered columnar phase are observed. Simulation procedures are used to investigate the phase behaviour and especially the microscopic structure of these lyotropic liquid crystal systems. The thermodynamic behaviour of our prototype molecular model shows a qualitative resemblance to experimental results obtained from aqueous solutions of the discotic amphiphile known as TP6EO2M.     

Laser-assisted generation of gold nanoparticles and nanostructures in liquid and their plasmonic luminescence

Nanoparticles (NPs) and surface nanostructures (NS) are produced via laser ablation of a bulk gold target in liquid using second harmonics of 10 ps Nd:YAG laser (532 nm) with repetition rate of 50 kHz. The morphology and plasmon photoluminescence (PL) properties of obtained nanoscale objects are described. Transmission electron microscopy and field emission scanning electron microscopy are used for morphology characterization of NPs and NS, respectively. Plasmon PL of both gold NPs and NS is experimentally studied using the third harmonics of the Nd:YAG picosecond laser (355 nm) as a pump. The wavelength of intensity maximum of PL of Au NPs colloidal solution virtually coincides with the position of Au NPs plasmon absorption peak. Real-time excitation of both plasmon PL and Raman scattering of surrounding liquid by picosecond laser pulses in aqueous colloidal solution is also investigated. The efficient cross section of plasmon PL of Au NPs colloid is evaluated using Raman scattering of water as a comparative parameter. The results are in good agreement with values obtained in previous works. Plasmon PL from self-organized NS on the Au surface produced via laser ablation is observed for the first time. Its spectrum is compared to PL spectra of both aqueous colloidal solutions of NPs and of NPs deposited on a Si wafer. The obtained experimental data are discussed with reference to the band structure of bulk Au.     

四磺酸基酞菁在溶液中的聚合平衡

用4－磺基邻苯二甲酸三铵盐与尿素在金属锑的催化下反应，合成了4，4′，4″,4″′-四磺酸基酞菁（H2TSPc)。用分光光度法对该化合物在溶液中的性质进行了研究。研究发现，溶剂、H2TSPc的浓度、溶液的pH，均对化合物的吸收光谱产生影响。本文对H2TSPc在水溶液中的存在形式进行了研究，并对溶剂性质、介质酸度等因素对H2TSPc在水溶液中的存在形式的影响作用及其机理作了探讨。     

The solution flow through the nanochannel of MCM-41: a spin-probe study

A spin-probe electron spin resonance (ESR) study was made on the alcoholic solution flowing through a quartz column packed with MCM-41 to clarify the dynamics of the liquid molecules in the nanochannel. The ESR spectra of a few hydrophobic spin probes showed that they undergo rotational diffusion preferentially along the longest molecular axis, indicating that the nanochannel is effectively narrowed further for these radicals by the influence of the solvent. Since almost identical ESR spectra were observed for the static samples, which were prepared in vacuo by introducing the solutions into the quartz tube with the MCM-41 powder and sealing off, the solution in the above-mentioned experiment should really flow through the nanochannel of MCM-41. Although a laminar flow is expected from the classical theory, the calculated flow rate is almost zero. In addition, the duration for the spin-probe molecules to flow through the column was basically not dependent on their affinity to the silica surface. To explain all these phenomena, we propose a model that the liquid molecules flow collectively by slipping on the surface of the nanochannel.     

Instability of a charged layer of a viscous liquid on the surface of a solid spherical core

The dispersion relation for the spectrum of capillary waves of a spherical layer of a viscous liquid coating a solid spherical core with a layer of finite thickness is introduced and analyzed. It is shown that the existence of two mechanisms for the viscous dissipation of the energy of the capillary-wave motions of the liquid, viz., damping in the bulk of the layer and on the solid core, leads to restriction of the spectrum of the realizable capillary waves of the liquid on both the high-and low-mode sides. At a fixed value of the system charge which is supercritical for the first several capillary modes, the maximum growth rates in the case of a small solid core are possessed by modes from the middle of the band of unstable modes, while in thin liquid layers the highest of the unstable modes have the largest growth rates. This points out differences in the realization of the instability of the charged surface of the spherical layer for small and large relative sizes of the solid core. Zh. Tekh. Fiz. 67, 8–13 (September 1997)     

(t-bt)2Ir(acac)新型磷光染料的光谱特性及电致发光性能研究

对不同浓度的新型黄色铱配合物磷光染料bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2']iridium (acetylacetonate)[(t-bt)2Ir(acac)]溶液和薄膜状态下的光致发光光谱(Photoluminescence,PL)和紫外-可见吸收(UV-Vis absorption)光谱进行了表征.结果表明,溶液浓度为3×10-4mol·L-1时的PL发光最强,浓度猝灭效应使得高浓度溶液的PL强度降低.薄膜的PL和吸收光谱相对溶液的光谱都发生了红移,这是由于固态时分子间距小、相互作用大,分子表现为聚集态的结果.基于光谱特性,制备了(t-bt)2Ir(acac)超薄层结构的电致发光器件,在13.2 V的偏置电压下,器件的发光亮度达到18 367 cd·m-2.     

1H NMR characterization of the product from single solid-phase resin beads using capillary NMR flow probes.

A capillary NMR flow probe was designed to generate high-resolution (1)H NMR spectra at 600 MHz from the cleaved product of individual 160-microm Tentagel combinatorial chemistry beads. By injecting a dissolved sample sandwiched between an immiscible, perfluorinated organic liquid directly into the probe, NMR spectra of the product cleaved from single beads were acquired in just 1 h of spectrometer time without diffusional dilution. Sample handling efficiency on the single bead scale was comparable to that obtained with a bulk sample. Using the relative intensity of the DMSO-d(5)H versus the analyte signals in a fully relaxed CPMG spectrum, the amount of product cleaved from a single bead was determined to be 540+/-170 pmol in one of the samples. Following the NMR data collection, the samples were examined with electrospray ionization mass spectrometry to provide additional structural information. By coupling with microliter-volume fluidic capabilities, the capillary flow probe described here will enable multidimensional characterization of single solid-phase resin products in an online manner.     

The 1H and 19F resonance spectra of 1-fluoro-2,4-dinitrobenzene

The ¹H and ¹⁹F resonance spectra of 1-fluoro-2,4-dinitrobenzene in pure liquid and in 5 mole per cent solutions in benzene and acetone were obtained and analysed by an iterative computer calculation. The results for the pure liquid are in good agreement with perturbation calculations performed on this spectrum earlier. It is shown that the deviation between the values of coupling constants obtained earlier in benzene solution, acetone solution and pure liquid are not due to the method of analysis.