超临界水的谱学研究进展

超临界水具有独特的性质，在理论和实际应用上都已经受到广泛的关注，超临界水的的静态结构和动力学的研究是认识其性质的理论基础，氢键是静态结构研究的一个重要的内容，在实验上主要是通过谱学的方法如拉曼光谱，核磁共振（NMR），以及衍射分析等进行，动力学研究是探讨其作为反应介质的机理研究的基础，微波波谱法，NMR法，以及准弹性不相干中子散射方法都用于对超临界水的分子动力学重排的研究。     

Spectroelectrochemical studies of poly-o-phenylenediamine Part 2. In situ UV—vis subtractive reflectance spectroscopy

In our previous paper, the phenazine-like structure of the poly-o-phenylenediamine (PoPD) and its three steady redox states have been revealed mainly by using in situ resonance Raman spectroscopy. It has also been shown that the semi-oxidized state of PoPD is the most stable state of PoPD, while the totally-oxidized state of PoPD is chemically unstable and can exist only at certain electrode potentials. In the present work, the more detailed reaction mechanism of a PoPD film in strong acid solution has been studied by using in situ UV—vis substractive reflectance spectroscopy. The semi-oxidized state and the totally-oxidized state of PoPD have electronic absorption bands around 300 nm, 430 nm, 500 nm and 300 nm, 450 nm, 530 nm, 735 nm respectively in the in situ steady state UV—vis subtractive reflectance spectra with respect to the reduced state of PoPD, which verifies once again that three redox states of PoPD exist in the redox process of PoPD. Moreover, the relative intensity between two oxidized states of PoPD at the maximum absorption wavelength (λ_max) reveals that only about one third of the semi-oxidized state of PoPD can be oxidized to the totally-oxidized state of PoPD. The in situ resonance Raman spectra and the cyclic voltammograms of PoPD display the same quantitative relationship. New absorption bands were observed in the in situ time-resolved UV—vis subtractive reflectance spectra with appropriate time resolutions, which illustrate the dynamic structure changes of PoPD in its redox process. These intermediate states of PoPD are more unstable than its three redox states.     

A DFG spectrometer at 3 μm for high resolution molecular spectroscopy and trace gas detection

We report the realization and characterization of a spectrometer based on difference frequency generation using a periodically poled lithium niobate crystal. As signal and pump lasers we used a diode-pumped Nd–YAG laser (λ=1.064 μm) and an extended cavity semiconductor diode laser (λ=0.785 μm), respectively. The mid-infrared coherent radiation was produced at 3 μm with a maximum power of about 160 nW obtained with 340 mW of signal and only 3.4 mW of pump. That corresponds to an efficiency of 0.01%/Wcm, which is in good agreement with other data available in literature. The generated radiation around 3 μm has allowed us to study fundamental absorption bands of molecules of great atmospheric and physical interest such as water vapor and the hydroxyl free radical. In this work we report preliminary spectroscopic results concerning the ν₁ 5₄₁→6₅₂ H₂O line at 2.968 μm. In particular, for this line we provide the first experimental estimation of self-, N₂- and O₂-broadening coefficients.     

CdSe量子点拉曼谱的共振效应研究

本文介绍了用共振拉曼光谱研究CdSe量子点材料的结果,认为拉曼峰是ZnSe和量子点界面模的叠加。指出当激发光能量逐渐离开ZnSe带隙时,共振减弱,ZnSe峰不再占主导,界面模的拉曼峰出现移动及变宽。     

二苄基锡炔基膦酸酯的红外光谱研究

研究了二苄基锡炔基膦酸酯的红外光谱，归属了这些化合物的特征红外吸收峰。     

红外光谱法在癌症早期诊断中的应用

傅里叶红外光谱法可用于细胞和组织等复杂体系的研究，本文主要综述了近年来傅里叶变换红外光谱法在癌症早期诊断中的应用探索。     

A theoretical analysis of the breakdown of electrostrictive oxide film on metal

Oxide films that form to protect (passivate) metal substrates from corrosive environments can be severely damaged when they are subjected to sufficient levels of electric potential. A continuum mechanics model is presented that captures the intimate electromechanical coupling of the environment and the film responsible for either growth or dissolution of the oxide. Analytical solutions, obtained for a finite-thick film experiencing a uniform electric field, illustrate the existence of a critical combination of electric field strength, initial film thickness and shape, beyond which the passivating oxide can become thin enough to undergo dielectric breakdown, or the substrate can become exposed to the corrosive environment. An experimental procedure is proposed to measure combinations of material properties required by the theoretical model to predict the lifetime of the oxide or to avoid the critical state. Illustrative numerical examples are provided to describe the morphological evolution of oxide films with a periodically wavy surface.     

Changes in the surface structure of Pd/Ta2O5 by oxygen and CO studied using X‐ray Photoelectron Spectroscopy (XPS)

Behaviors of Pd structures with different thicknesses supported by Ta₂O₅/Ta in the reaction with oxygen and CO were studied by XPS and SEM. For the samples with a Pd thickness of 3 nm, a new low‐binding‐energy component appeared in the Pd 3d level upon O₂ exposure at ～200 °C and was reduced in intensity after a subsequent CO exposure at 150 and 200 °C. The change in the Ta 4f state could also be found upon oxygen and CO exposure, indicating that both Pd and the Ta‐oxide substrate participate in the chemical reactions. For the sample with a higher Pd thickness, a positive shift in the Pd 3d level due to the oxidation of Pd was observed after exposure to O₂ at a higher temperature (280 °C). A subsequent CO exposure at ～150 °C could not reduce Pd‐oxide layers, as confirmed by the unchanged Pd 3d spectra after CO treatment, i.e. Pd‐oxide was not reactive for CO oxidation. Copyright © 2010 John Wiley & Sons, Ltd.     

The free volume in acrylic resin/laponite nanocomposite coatings

The morphological features and the free volume properties of an acrylic resin/laponite nanocomposite are investigated using X-ray diffraction and Positron Annihilation Lifetime Spectroscopy. The effects of particle loading on the degree of exfoliation is examined. The measured lifetime spectra and the relative intensities of samples with different particle loading, as well as the shape parameters of the Doppler line broadening are correlated to the free volume in the nanocomposite and the measured CO₂ gas solubility. The effect of the exfoliated nanoclay on the free volume of the composite is found to be very small for clay volume fraction up to 0.2%.     

Spin Trapping of Radical Intermediates Generated by the Oxidation of Substituted 4‐Methylphenols

A series of substituted 4‐methylphenols 1 and 2 was oxidized with PbO₂ in the presence of nitroso compounds 3 – 10 . The formation of adducts of benzyl radicals with the nitroso spin traps in the reaction mixture was established, suggesting the abstraction of an H‐atom from the methyl substituent of 1 or 2 . In the consecutive steps, the adducts underwent a further rearrangement to the corresponding nitrones. When the starting phenol contained bulky ^tBu groups in ortho‐position (see 2,6‐di(tert‐butyl)‐4‐methylphenol ( 1a )), the stable 2,6‐di(tert‐butyl)‐4R‐phenoxy radicals (R=? CH?N⁺(O^?)? X) were detected as the final radical products. The indirect evidence of nitrones in the reaction mixture was performed in one case by the reaction with a RO radicals.