Robust self-assembled octadecylphosphonic acid monolayers on a mica substrate

As determined by scratch tests, self-assembled monolayers (SAMs) of octadecylphosphonic acid (OPA) on a muscovite mica substrate were found to be mechanically robust and to serve as a lubricant to protect the underlying mica substrate. For comparison purposes, three polymer films were subjected to scratch tests under the same conditions. The scratch tests were conducted using a diamond-tipped stylus, and the resultant scratches were examined using atomic force microscopy. The excellent mechanical strength of OPA SAMs is supported by analysis with time-of-flight secondary ion mass spectrometry, which suggests that the headgroup of the OPA is strongly bonded to the substrate atoms. The molecular lubrication provided by OPA SAMs suggests that the interaction between the headgroup and the substrate is sufficiently strong to endure significant shear force and that the hydrocarbon chains are able to dissipate shear energy.     

压电石英晶体在电解质水溶液中的振荡性能研究(Ⅱ)——频率、频移特性

根据两面电极浸入液体中的压电晶体等效电路模型和Pierce振荡器振荡方程的解,得到晶体在电解质溶液中的振荡频率(F_1)与溶液电导率(x)的关系式:F_1=(1/2π)(1/C_1+1/C_2)(1/X_e)[(R_e~2+X_e~2)x~2+2R_ex+1]。以自行设计的Pierce晶体振荡器。研究了晶体和主振电路参数、输入电压及检测池外壳屏蔽接地对AT切9MHz石英晶体在KCl、Na_2SO_4水溶液中的频率、相对于纯水频移随溶液电导率变化的影响规律,结果与上式相符。     

Mass spectrometric study of six cyclic esters

A series of cyclic esters, which are optically active as a consequence of their helical structures, were synthesized to investigate the relationships between their structures and their optical activities. This paper reports the electron impact fragmentation mechanisms of these six cyclic esters. Accurate mass measurements and mass analyzed ion kinetic energy spectrometry confirmed fragmentation patterns. The stability of the fragment ions has a great influence on the fragmentation pathways, but no correlation with the optical activity was found.     

Synthesis of New Spiropyrans With a Polyaromatic or Heteroaromatic Pendant and Their Photochromic Bedhaviors

A series of spiropyrans with a polyaromatic or heteroaromatic pendant was synthesized conveniently.Their photochromic behaviors were investigated with the aid of absorption spectral measurements.The results indicated that the compounds with the same parent spiropyran but different aromatic pendant show significantly different photochromic properties.This may be due to the π-π orbital interaction between the polyaromatic pendant and the open photomerocyanine form of spiropyran.The results obtained are very useful in the molecule design area.     

Diaquabis(2,5‐dihydroxybenzoato‐κO)bis(1,10‐phenanthroline‐κ2N,N′)strontium(II) bis(1,10‐phenanthroline) tetrahydrate

The title compound, [Sr(C₇H₅O₄)₂(C₁₂H₈N₂)₂(H₂O)₂]·2C₁₂H₈N₂·4H₂O, consists of an Sr^II complex, uncoordinated phenanthroline (phen) molecules and solvent water molecules. The Sr^II ion is located on a twofold axis and is coordinated by two phen ligands, two dihydroxybenzoate anions and two water molecules in a distorted tetragonal antiprismatic geometry. Partially overlapped arrangements exist between parallel coordinated and parallel uncoordinated phen rings; the face‐to‐face separations between the former (coordinated) and the latter (uncoordinated) rings are 3.436 (13) and 3.550 (14) Å, respectively. This difference suggests the effect of metal coordination on π–π stacking between phen rings.     

Simulation of Three-Spin Interaction in Coupled Cavities Chain

We generalize usual second-order effective Hamiltonian approximation into third-order. Employing the generalized method, we propose a scheme to generate three-spin interaction using coupled cavity chain. We show that the third order term not only improves two parties interaction but also induces direct three-spin interaction which has not been simulated before. By controlling the frequency of laser field, one can obtain next nearest neighbor interaction on the same order with the nearest neighbor’s or the three-spin interaction on the same order as next nearest neighbor’s.     

镝掺杂LaPO4拉曼光谱变化规律的探讨

采用水热法和后续热处理合成出单斜相LaPO4以及LaPO4:Dy3+,通过XRD对样品进行物相分析,结果表明:所得样品为LaPO4,且XRD图谱及拉曼光谱中峰位的偏移表明Dy的存在,即Dy被掺杂到LaPO4基质中。通过研究用Dy对LaPO4进行不同量掺杂后其拉曼光谱的变化规律,进而找出用Dy对LaPO4进行不同量掺杂后其内部结构的变化规律。结果显示,用Dy对LaPO4进行不同量掺杂后,随着掺杂比例的增大,晶格畸变程度先上升后下降,且在镧镝物质的量比例为1∶0.06时对基体晶格结构影响最大。