Interaction and local magnetic moments of metal phthalocyanine and tetraphenylporphyrin molecules on noble metal surfaces

In order to understand the Kondo effect observed in molecular systems, first-principles calculations have been widely used to predict the ground state properties of molecules on metal substrates. In this work, the interaction and the local magnetic moments of magnetic molecules （3d-metal phthalocyanine and tetraphenylporphyrin molecules） on noble metal surfaces are investigated based on the density functional theory. The calculation results show that the dz2 orbital of the transition metal atom of the molecule plays a dominant role in the molecule-surface interaction and the adsorption energy exhibits a simple declining trend as the adsorption distance increases. In addition, the Au（111） surface generally has a weak interaction with the adsorbed molecule compared with the Cu（ll 1） surface and thus serves as a better candidate substrate for studying the Kondo effect. The relation between the local magnetic moment and the Coulomb interaction U is examined by carrying out the GGA＋U calculation according to Dudarev＇s scheme. We find that the Coulomb interaction is essential for estimating the local magnetic moment in molecule-surface systems, and we suggest that the reference values of parameter U are 2 eV for Fe and 2-3 eV for Co.     

酞菁铜衍生物在酞菁酮—氧化铁纳米粒子交替LB膜中的分子取向

通过Langmuir-Blodett技术制备了酞菁酮－氧化铁纳米粒子交替LB膜,利用偏振紫外－可见光谱对酞菁铜衍生物在不同制膜条件下所制得的交替膜中的分子取向进行了研究。结果表明,在同一氧化铁溶胶亚相中,随着表面压的增大,或在相同的表面压下,随着亚相中氧化铁浓度的减小,酞菁铜分子在其复合LB膜中倾斜程度变大。     

Effect of hydrostatic pressure on self-diffusion in metal nanoparticles

The thermodynamics approach has been developed to describe the self-diffusion in nano-sized solids. It has been established that identical homologous temperatures of metal nanoparticles with their fixed characteristic size give the identical coefficients of diffusion under different pressures. The dependence of the activation enthalpy of diffusion on pressure and on the characteristic size of nanoparticles is first obtained.     

Effect of hydrostatic pressure on self-diffusion in metal nanoparticles

The thermodynamics approach has been developed to describe the self-diffusion in nano-sized solids. It has been established that identical homologous temperatures of metal nanoparticles with their fixed characteristic size give the identical coefficients of diffusion under different pressures. The dependence of the activation enthalpy of diffusion on pressure and on the characteristic size of nanoparticles is first obtained.     

Effect of crystal field on the spin density at the copper nucleus in copper complexes

The role of lower symmetry component of the crystal field in causing a mixing of excited 3d ^x−1 4s with the ground 3d ^x configuration and leading to spin density at the nucleus for iron group ions was suggested by Griffith and Orgel. This mechanism has been examined in detail for the two low-symmetry copper complexes, one square planar (D_4h symmetry) and the other distorted tetrahedron (D_2d symmetry) and the calculation has been performed using the powerful Racah method and tensor operator technique. It is found that for the two types of copper complexes, copper pthalocyanin (square planar, D_4h symmetry) and cesium copper chloride (distorted tetrahedron, D_2d symmetry) the contribution from this mechanism to the spin density at the nucleus vanishes identically.     

Vermiculite decorated with copper nanoparticles: Novel antibacterial hybrid material

Vermiculite decorated with copper nanoparticles is a new antibacterial material that was prepared in this study through ion-exchange process and hydrogen reduction. The replacement of magnesium ions in interlayer structure was carried out using concentrated copper sulfate solutions at elevated temperature. Copper ions were reduced to elemental copper at 400-600 °C using hydrogen as the reducing agent. During the reduction process copper diffused primarily to vermiculite surface regions and formed copper nanoparticles with a broad range of sizes, from ∼1 to 400 nm. Strong adhesion of copper nanoparticles to the vermiculite carrier makes this hybrid very stable and durable. The new vermiculite-metallic copper hybrid material shows strong antibacterial activity against Staphylococcus aureus at 37 °C. Vermiculite is an inexpensive mineral that is very stable under a wide range of industrial and environmental conditions, and extensively used as filler in fireproof materials, plastics, paints and lightweight concrete, so the addition of copper as an antibacterial agent opens new avenues for the application of vermiculite in consumer products and other areas.     

Laser-driven metal exchange and preparation of metal phthalocyanine

Two types of laser-driven dry processes for the preparation of metal phthalocyanine are reported. In the first one, laser-driven metal exchange, the excimer laser beam was focused on a copper target, and ablated copper atoms were injected onto a thin film of dilithium phthalocyanine (Li₂Pc). The central metal atoms of Li₂Pc were partially exchanged by copper atoms, and the blue thin film of copper phthalocyanine (CuPc) was obtained after removal of the residual Li₂Pc by the hydrochloric acid treatment. In the second one, direct synthesis using the component organic molecule, CuPc was prepared by the implantation of laser-ablated copper atoms onto a thin film of 1,3-diiminoisoindoline (D I I I).     

Twin—layer films of copper phthalocyanine and amorphous titanyl or vanadyl phthalocyanine

Metallophthalocyanine (MPc) twin-layer thin films on glass substrates, consisting of copper phthalocyanine (CuPc) overlayer and amorphous vanadyl phthalocyanine (VOPc) as well as titanyl phthalocyanine (TiOPc) buffers, were found to have different gas sensing characteristics. These twin-layer thin films were studied using x-ray photoemission spectroscopy. Photoelectrons of either V or Ti core levels were found to be present at the surface, indicating the existence of possible molecular migrations. The stability of the twin-layers under thermal annealing up to a maximum temperature of 250℃ and low-energy Ar ion bombardment was also examined and compared with that of CuPc directly grown on the substrates. We concluded that the twin-layer structures were thermally fairly stable. Ar ion bombardment, however, caused substantial damage to the Pc ligands and a reduction of the valence state of the central Cu atoms.     

酞菁铜成膜特性的多重分形谱

运用多重分形理论,研究了酞菁铜颗粒的团聚生长成膜特性.研究表明薄膜生长是远离平衡态过程,在团聚生长中,颗粒分布有很大随机性,存在大范围的非均匀区域,这些区域具有多重分形特征.测试了酞菁铜对二氧化氮的气敏特性,结果表明通气前后,涂膜通道的频率有明显移动.     

Photophysical properties of pyridyloxy phthalocyanine encapsulated in nanoparticles

Two aluminum chloride phthalocyanines with pyridyloxy substitution at α/β positions were synthesized. Their structures were characterized by infrared spectroscopy, proton nuclear magnetic resonance as well as elemental analysis. Tetra-α(β)-(2-pyridyloxy) aluminum chloride phthalocyanines were encapsulated into a diblock copolymer methoxy-poly(ethylene glycol)-block-poly(L-lysine) through a cosolvent method. The morphologies and photophysical properties of phthalocyanines encapsulated in nanoparticles were studied by transmission electron microscope, ultraviolet-visible, and fluorescence spectroscopic methods. The photophysical properties of phthalocyanines encapsulated into nanoparticles exhibited substitution positions dependence. The phthalocyanines with substitution at α positions were found to be an excellent candidate for use as photosensitizers for treatment of cancer by photodynamic therapy.     

酞菁铜染料的反饱和吸收动力学

本文用速率方程研究了酞菁铜染料氯仿溶液的反饱和吸收的动力学过程,并用YAG倍频调Q脉冲激光入射该样品,验证了理论.通过理论曲线与实验结果的拟合,估算出酞菁铜三重态激发态的吸收截面为2.6×10~(-17)cm~2.     

Effect of pressure on melting and solidification of metal nanoparticles

A thermodynamic model was developed to clarify the dependence of melting temperature on hydrostatic pressure in the nanoscopic scale. It is based on the classic Clausius-Clapeyron relation and the size dependence of the melting entropy. The melting of nanoparticles in matrix with coherent and incoherent boundaries was also under consideration. It was shown that external hydrostatic pressure leads to the appearance of extrema of the melting temperature that was considered as a function of the characteristic size of nanoparticles.     

Effect of metal nanoparticles on the thermal stability and conductivity of nanocomposites

The thermogravimetric parameters of the thermal degradation of nanocomposites containing noble metal (Ag, Au, Pd, and Pt) nanoparticles in the arabinogalactan matrix are estimated. The effect nanoparticles have on the electrical conductivity of nanocomposites with the arabinogalactan dielectric matrix is investigated in detail.     

Silver on copper phthalocyanine: Abrupt and inert interfaces

The chemistry and electronic structure evolution were studied upon the formation of the interfaces between copper phthalocyanine and Ag and Sn deposited on it in ultra high vacuum conditions. The measurements were performed by means of high-resolution photoemission spectroscopy of core-levels and the valence band, and using synchrotron-radiation facilities. The investigations demonstrate the formation of chemically inert and abrupt interfaces.     

Influence of thermal treatment on the performance of copper phthalocyanine thin-film transistors

Organic thin-film transistors (OTFTs) with bottom-gate and bottom-contact configuration based on copper phthalocyanines (CuPc) as active layer were fabricated. The performance of CuPc OTFTs was studied before and after thermal treatment on CuPc layer. The values of the threshold voltage before and after thermal treatment are −6.3 and −5.7 V, respectively. The field-effect mobility values in saturation regime of CuPc thin-film transistors before and after thermal treatment are 0.014 cm²/Vs and 0.0068 cm²/Vs, respectively. The experimental results indicate that there is a heavy decay on the mobility of CuPc based OTFTs mostly due to the crystalline morphology change induced by the thermal treatment, and absolute value of the threshold voltage after thermal treatment decreases with the decrease of the CuPc film thickness and the roughness.     

Ferroelectric phase transition in Langmuir-Blodgett films of copper phthalocyanine

A ferroelectric phase transition is observed in Langmuir-Blodgett films prepared from substituted copper phthalocyanine molecules. The linear and nonlinear dielectric properties of the films and the switching of their spontaneous polarization are investigated in the temperature range of the phase transition. The observed features can be explained by the Landau-Ginzburg model of a first-order phase transition. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 9, 625–631 (10 November 1999)     

激光辐照环境对金属材料反射特性的影响

 利用积分球绝对测量法,对在20 Pa真空缺氧、1 000 Pa空气,10⁵ Pa空气及1 000 Pa氧气环境下,1 064 nm波长连续激光辐照30CrMnSiA碳钢材料过程中的反射光信号进行了测量,得到了30CrMnSiA碳钢在4种辐照环境下的反射率和温度变化曲线。结果表明：在空气组分辐照环境的低压到10⁵ Pa范围内,材料初始反射率随压力增大而增大;在缺氧和富氧环境的激光辐照过程中,缺氧环境下材料反射率变化缓慢,且变化拐点温度高于富氧环境,富氧环境下材料被加热后的快速氧化反应有利于材料对激光能量的吸收;不同辐照环境（缺氧和富氧）相同材料温度条件下,材料反射率并不相同。     

Effect of a local field on the spectra of autoionization resonances

The change of the spectral parameters of a single autoionization resonance with concentration in gaseous media is studied in terms of the isotropic Lorentz-Lorenz model. It is shown that the effect of a local field may result in a shift, narrowing, or broadening of the resonance, as well as in a change in its amplitude and the character of interference of the discrete state with the continuum. By appropriate selection or variation of the partial pressures of substances in the mixture, the separation of a particular regime is possible. An analogy to the laser-induced narrowing of autoionization resonances is drawn.