氟化高分子材料的光学特性及其应用

高分子材料在光电子领域是一种必不可少的材料。由于含氟化合物中分子吸收受到抑制及分子极化率降低等原因,导致氟化高分子材料在近红外光区具有优良的透明性,并且折射率很低,这对于高分子光学元件的设计具有重要意义。     

氯霉素在电解法制备纳米银膜上的表面增强拉曼光谱的研究

用电解法制备了一种纳米银膜, 并用扫描电镜和透射电镜进行了研究。我们得到了银膜上的氯霉素的SERS谱, 并且用gaussian’98软件对氯霉素的Raman谱进行了运算, 发现实验结果和理论计算结果有很好的相似性。本实验说明电解法制备的纳米银膜对于检测氯霉素有很好的应用前景。     

刃边法检测空间相机MTF的方法研究

空间相机的MTF是描述成像系统的空间频率响应特性的重要指标之一。在介绍刃边法计算空间相机MTF原理的基础上,描述了刃边法的计算过程,结合天绘一号卫星在轨传感器MTF检测,对高分辨率相机的MTF进行了计算。结果表明,刃边法检测卫星相机MTF的方法可行,能够获得较好的评价结果。     

On the influence of lattice vibrations on the tunnel-current in normal metals

Energy spectra of 50 kev-electrons scattered inelastically in thin Al foils of various thicknesses have been measured as a function of scattering angle. The measured angular distribution of electrons which have excited one or more volume plasmons is compared with theoretical calculations and good agreement is obtained. From the integrated intensities, the mean free path of 50 kev-electrons for plasmon excitation is determined with an accuracy of about 20%. The resulting value Λ=820 Å is in good agreement with the theoretical value calculated fromFerrell's free electron model (Λ=760Å).     

Oscillateur paramétrique optique intégré : revue des réalisations sur niobate de lithium polarisé périodiquement

To realize an IOPO, one need a good nonlinear substrate in which it is possible to realize low-loss waveguides and fulfill the phase-matching conditions. In this paper, I will present the problems researchers have faced, the techniques they have used and the results they have obtained by using either proton exchange or titanium indiffusion to create waveguides in periodically poled lithium niobate.     

Efficient Entanglement Concentration of Nonlocal Two-Photon Polarization-Time-Bin Hyperentangled States

We present two different hyperentanglement concentration protocols (hyper-ECPs) for two-photon systems in nonlocal polarization-time-bin hyperentangled states with known parameters, including Bell-like and cluster-like states, resorting to the parameter splitting method. They require only one of two parties in quantum communication to operate her photon in the process of entanglement concentration, not two, and they have the maximal success probability. They work with linear optical elements and have good feasibility in experiment, especially in the case that there are a big number of quantum data exchanged as the parties can obtain the information about the parameters of the nonlocal hyperentangled states by sampling a subset of nonlocal hyperentangled two-photon systems and measuring them. As the quantum state of photons in the time-bin degree of freedom suffers from less noise in an optical-fiber channel, these hyper-ECPs may have good applications in practical long-distance quantum communication in the future.     

Measurement of the velocity distribution of neutral atoms using laser-induced fluorescence

Laser-induced fluorescence has been used to measure the Doppler-shifted emission spectra in the atomic beam of gadolinium. The velocity distribution of gadolinium atoms that was deduced from these spectra shows good agreement with a Maxwellian distribution. Based on this good agreement, temperatures of the evaporating source have also been estimated. A new experimental method has been devised in our measurements, which can also be used for other multiline systems similar to gadolinium. This method allows one to effectively eliminate the distorting interference present in Doppler profile measurements for the multiline systems mentioned above. The text was submitted by the authors in English.     

Transport properties of He-CO mixtures

Classical trajectory calculations for the collision of He with CO have been carried out, with CO treated as a rigid rotor, for two similar potential energy surfaces, one obtained from high level ab initio calculations and the other from a semi-empirical fit to the infrared spectra of He-CO van der Waals dimers. Second-approximation corrections to the kinetic-theory expressions have been employed in order to carry out comparisons with the most accurate and precise diffusion, shear viscosity, thermal conductivity and thermal diffusion data available. Rotational relaxation data are also considered. Both potentials are found to have good predictive power for these transport and relaxation properties, giving on the whole very good agreement with the experimental data. This indicates that the isotropic components of the two potential surfaces are very similar, and that the anisotropies are not significantly different. It is suggested that the measurement of additional relaxation phenomena in He-CO mixtures could allow a clearer distinction to be made between the two potential surfaces.     

Excess-noise suppression in a fibre-optic balanced heterodyne detection system

We have investigated balanced heterodyne detection in applications where laser intensity fluctuations are the dominant noise source, as, for example, in laser Doppler velocimetry with a He-Ne laser. The suppression of excess noise in comparison with a single receiver detection system is analysed theoretically. In our heterodyne experiment we have compared two different fibre-optic Mach-Zehnder interferometers, both with single-mode polarization-preserving fibres, one in integrated form using a directional coupler, the other one with a dielectric beam-splitter as the optical mixing element. With the former we have verified the theoretical results; with the latter we have demonstrated that with a good balance the fundamental short noise detection limit can be reached.     

On the photoelectron spectrum of sulphur trioxide

He(I), He(II) and variable temperature Ne(I) photoelectron spectra of sulphur trioxide are reported. All six of the expected ionic states have been detected and assigned; the assignment differs from a previous one. Ab initio calculations in a medium basis set have been carried out and spectral intensities have been calculated; agreement between the calculations and the spectra is good. The calculations show a substantial S(3d) character in the S-O bond, and the spectra are consistent with this.     

Comparison of pulse amplification performances in longitudinally pumped Ytterbium doped materials

Using a theoretical model, the amplification of laser pulse performances achievable with various Ytterbium doped longitudinally pumped materials is compared. The investigated materials have been separated into two categories: some of them seem to be well suited for diode pumping as they allow good extraction efficiency when pumped by low pump intensity and long pulses. For the others, high pump intensity even with short pulses is required for achieving good extraction efficiency and they can be efficient when pumped by laser. It appears that the classification of these host materials is different from the one set for CW or pulsed lasers.     

Hydrodynamic description of laser-induced coulomb explosion for small molecules

We have performed extensive numerical studies of Coulomb explosion of small molecules such as CO2 and N2O with the help of a hydrodynamic model, which allows one to deal with many-electron systems in intense laser fields. The predicted kinetic energy releases of the fragmentation channels are in good agreement with the measured energies, using realistic molecular and laser excitation condition parameters.     

The electronic bandstructure of rhodium and the effects of change of volume

The electronic bandstructures of fcc rhodium have been calculated for the normal value of the lattice constant and one 5% smaller, using the nonrelativistic symmetrized augmented plane wave method. The results of the first calculation are in good agreement with those of other workers. Under pressure the d-bands shift and broaden appreciably, resulting in a slight increase in d-occupation.Dedicated to Professor Miroslav Trlifaj on the occasion of his sixtieth birthday.     

Dynamics of the Langevin model subjected to colored noise: Functional-integral method

We have discussed the dynamics of Langevin model subjected to colored noise, by using the functional-integral method (FIM) combined with equations of motion for mean and variance of the state variable. Two sets of colored noise have been investigated: (a) one additive and one multiplicative colored noise, and (b) one additive and two multiplicative colored noise. The case (b) is examined with relevance to a recent controversy on the stationary subthreshold voltage distribution of an integrate-and-fire model including stochastic excitatory and inhibitory synapses and a noisy input. We have studied the stationary probability distribution and dynamical responses to time-dependent (pulse and sinusoidal) inputs of the linear Langevin model. Model calculations have shown that results of the FIM are in good agreement with those of direct simulations (DSs). A comparison is made among various approximate analytic solutions such as the universal colored noise approximation (UCNA). It has been pointed out that dynamical responses to pulse and sinusoidal inputs calculated by the UCNA are rather different from those of DS and the FIM, although they yield the same stationary distribution.     

Hartree-Fock calculations of surface-symmetry properties with finite-range forces

Complete Hartree-Fock calculations on asymmetric semi-infinite nuclear matter have been performed with a family of finite-range Gogny-type forces. For one of these forces all the computed values of the droplet-model symmetry coefficients J, L, M and Q are in good agreement with recent mass-formula fits.     

Measured sensitivity of arc-induced long-period grating sensors in photonic crystal fibre

Reported are experimental results from investigations of the sensing properties of long-period gratings (LPGs) recorded in two different geometries of photonic crystal fibre (PCF): a large-mode area PCF and an endlessly single mode PCF. The LPGs have been characterised for their sensitivity to temperature, bending, surrounding index and strain. The LPGs in both fibres have been found to have negligible temperature sensitivity whilst exhibiting useful strain sensitivities. Strong directional bend sensitivity is shown by one PCF whilst the other shows good non-directional bend sensitivity. The fibres exhibit differing sensitivities to surrounding refractive index.     

HIV蛋白酶多肽抑制剂的理论研究

艾滋病病毒的发现距今已有二十多年的历史了.它仍然以很快的速度在全球范围速蔓延.研发抗艾滋病药物是当代药学的重大课题之一.在以往研究的基础上,我们利用分子叠合和分子对接这两种分子模拟手段,把从PDB数据库中得到的与HIV蛋白酶结合的12个肽类分子和已经上市的抗艾滋病的药物Saquinavir做比较.根据结构相同或相近的分子具有相同的活性原理,运用分子叠合初部判断分子活性,特别是药效团的特征比对揭示了分子活性的原因,为进一步的药物设计奠定了良好的基础.进而采用分子对接的分子模拟方法对这12个肽类分子的活性构象进行了深入的分析,预测出了这12个分子对HIV病毒蛋白酶的不同抑制作用.研究发现:P01、P05、P09、P12可能与已知药物Saquinavir在与HIV蛋白酶结合时具有相似的活性,其中P9的活性最强,有望成为抗HIV药物的理想前体,为下一步的HIV药物的设计研究提供了理论依据.     

油气藏三维三相组分模型软件研制与应用

提出了一种对压力和饱和度隐式、组分摩尔分数显式的部分隐式组分模型求解方法。该方法所需联立求解的方程组数量少,且兼有全隐式收敛性好的特点。通过与引进软件用相同地质模型、PVT资料对柯克亚X₅¹(3)凝析气藏循环注气进行模拟对比研究,验证了自编的部分隐式组分模型软件计算结果的可靠性,标志着自主版权的组分模型软件已经开始走向成功。