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Ni promoter was introduced into the co-precipitated FeMnK/SiO 2 Fischer-Tropsch synthesis catalysts. The effects of Ni on catalyst structural properties, reduction and carburization behaviors were studied by N 2 physical adsorption, XRD, Mossbauer spectroscopy, temperature programmed reduction (TPR) in H 2 and CO, and isothermal reduction in syngas. The results indicate that Ni promoter increases the BET surface areas of catalysts and is favorable to the formation of smaller crystallite particles. H 2 -TPR results show that Ni decreases the reduction temperature of catalysts, and CO-TPR results show that Ni facilitates the oxygen removal and increases the carbon introduction content. These effects contribute to a significant improvement of the reduction and carburization behaviors of catalysts in syngas, and the promotion effect increases with the Ni loading content.

Electron correlation in triple differential cross sections for ionization of atomic hydrogen by electron impact is analysed for the case of coplanar asymmetric geometry within the framework of the two-potential formulae. Based on the approximations of projectile and faster-electron plane wave, the transition matrix element is analytically expressed to be a product of two factors: the correlation factor of two electrons in the final channel and the structure-scattering factor. The contribution of both the factors to the angular distribution of the triple differential cross section is calculated. The present results are compared with the experimental data and the other theoretical calculations for the incident energy of 150eV.

A novel model is proposed to study the ionization of atomic hydrogen by fast election impact in coplanar asymmetric geometry making use of the post form of the transition matrix element for the energy shell and the two-potential formula. Based on the approximation of projectile plane waves and three-body problems, the transition matrix element is decomposed into two parts: the structure and scattering factor and the correlation factor. The contributions of these factors to triple differential cross sections are investigated using the method of asymptotic and convergent series.

An analytic expression for the ionization amplitude of hydrogen by electron impact is found to contain a polynomial by an optimal truncation in an asymptotic series and a convergent series. The ionization amplitude, i.e., the transition matrix element on the energy shell, is decomposed into two parts: the structure-scattering factor and correlation factor, based on an approximation of the projectile plane wave in coplanar asymmetric geometries. The contribution of these factors to the triple differential cross section is evaluated using the method of optional truncation of asymptotic and convergent series.

According to the analysis of gain theory, the absorption or gain of medium depends on pump power. The coherent population oscillation leads the pulse to experience absorption saturation and propagation delay in a medium with absorption. This effect induces the pulse to experience gain saturation and propagation advance in a medium with gain. Making use of the transition rate equation of metastable state poplation, we develop the model of fast light in erbium-doped optical fiber and obtain the analytic expression of time advance. We demonstrate that there is a saturation effect of fast light in low frequency region, but the fast light is enhanced with pump power increasing in high frequency region.

Because of the absorption of erbium-doped optical fiber, the group velocity of the optical pulse propagation is slowed down and the intensity of signal is reduced, which brings more difficulties to the actual measurement of slow light and its application in communications, such as the distortion and the low measurement.Therefore only after the group velocity slowdown of light pulse in erbium-doped optical fiber under no absorption loss is realized, can the slow light technology really have the practical application. We investigate the erbium-doped optical fiber amplifier deeply and develop a technology, in which the different pump powers and fiber lengths are used to reduce the signal loss through theoretical calculation and realize the group velocity slowdown of light pulse. The results show that no absorption loss is realized at a pump power of 3.5 mW, and we realize the slow light with a fiber length of 0.1 m when the pump power is zero.