载有卟啉的介孔SBA-15表面光电压的性质研究

用表面光电压谱(SPS)和场诱导表面光电压谱(FISPS)技术对比研究了卟啉和介孔SBA-15及载有卟啉的介孔SBA-15的表面光伏特性.固载后同时显示了卟啉和介孔的光电压性质,但是光电压响应强度减弱,这是因为卟啉和介孔之间发生了电子传递的缘故.在外电场诱导下,它们的光伏响应强度随外加正电场光伏响应强度的增加而增强,随外加负电场光伏响应强度的增加而减弱.而装载后的SBA-15在334和425 nm处的光伏响应信号随外加电场的变化而有不同的变化.     

A simple coupled mode model for near band-edge phenomena in grated waveguides

The paper presents a simple coupled mode model to describe near band-edge phenomena in the spectral response of waveguides with a section containing a rectangular grating. It is shown that nearly all relevant parameters can be determined in reasonable approximation from only the dispersion curve and one adjustable, proportionality constant. The theory is compared with results from numerical calculations and experiments.     

Cross sections for energetic heavy-ion impact on protonated water clusters

Energetic impact of multiple ionized oxygen on protonated water clusters in the range of eight to twenty-one water molecules is investigated on the ZERNIKE--LEIF facility. The target water clusters are stored in a Paul trap and thermalized by cold buffer gas. This well-controlled approach allows for a direct measurement of the total inelastic cross section leading to trap-loss processes of the target ions.     

W-代数W(2,2)的单参数量子形变(英文)

众所周知,泛包络代数的量子形变所对应的量子群结构是依据所给代数的单根系给出的.我们构造了q-形变W代数Wq,并给出其非平凡的量子群结构.     

Quantification of ion-induced molecular fragmentation of isolated 2-deoxy-D-ribose molecules

Recent experiments on low energy ion-induced damage to DNA building blocks indicate that ion induced DNA damage is dominated by deoxyribose disintegration (Phys. Rev. Lett., 2005, 95, 153201). We have studied interactions of keV H+ and He(q+) with isolated deoxyribose molecules by means of high resolution time-of-flight spectrometry. Extensive statistical fragmentation of the molecules is observed. The fragment distribution is found to follow a power law dependence. The exponent can be used to characterize and quantify the molecular damage.     

Visualizing the whispering gallery modes in a cylindrical optical microcavity

Whispering gallery modes in cylindrical integrated optics microcavities have, for what is to our knowledge the first time, been mapped with a photon scanning tunneling microscope. Optical images were obtained with a spatial resolution of 50 nm. By combination of information on the spatial optical distributions with wavelength-dependent measurements, an unexpectedly rich variety of intracavity phenomena, such as polarization conversion and interference of copropagating and counterpropagating modes, could be directly observed. A quantitative comparison of the experimental data with computer simulations results in a comprehensive understanding of the various whispering gallery modes inside the microcavity.     

Modelling of self-aligned total internal reflection waveguide mirrors: an interlaboratory comparison

Results of modelling of light propagation in 45° self-aligned total internal reflection rib waveguide mirrors on InP substrate are compared. Six laboratories participated in the comparison with the following six modelling methods: the standard fast-Fouriertransform beam propagation method (BPM), the standard finite-difference (FD) BPM using the Crank-Nicholson scheme (two laboratories), the FD-BPM with the correction for the slowly varying envelope approximation, the method of lines, the eigenmode expansion and propagation method, and a simple method based on the field overlap. All the laboratories used the effective-index method to reduce the three-dimensional problem to two dimensions. The differences among the results obtained by different methods are briefly discussed and qualitatively compared to measured values.     

Limit theorems for Markov chains of finite rank

We consider a Markov chain with a general state space, but whose behavior is governed by finite matrices. After a brief exposition of the basic properties of this chain, its convenience as a model is illustrated by three limit theorems. The ergodic theorem, the central limit theorem, and an extreme-value theorem are expressed in terms of dominant eigenvalues of finite matrices and proved by simple matrix theory.     

Informal Networks and Absenteeism Within an Organization

This article discusses the relationship between the informal ties of the employees within an organization and their absentee rates.~To explain this relationship, the assumption is made that within a department, a more or less stable norm concerning illegal absenteeism exits, and that the strength of this norm is related to the tightness of the informal relationships between the employees: the more consensus on the absentee norm, irrespective of the degree of tolerance, the more cohesive this department. Furthermore, according to the fairness theory of Adams (1965), a relationship between the tightness of the informal relations, the norm concerning illegal absenteeism and the absentee rate is expected: the more cohesive, the higher the effect of the group norm on the short-term absentee rate. Network data of 62 employees of eight comparable teams within a housing corporation were collected by means of a questionnaire, and combined with data on the absentee rates of the employees. The data supported the hypotheses concerning the relationship between the group norm, the tightness of the informal relations and the short-term absentee rates of the employees within a department.