本文利用双色–光发射电子显微镜(Photoemission Electron Microscopy, PEEM)成像了电子束加工的金纳米环样品的等离激元近场分布。利用双色的实验方法有效地打开了双色量子通道,从而导致发射电子的非线性阶次从3.80降低到1.85,并且光...本文利用双色–光发射电子显微镜(Photoemission Electron Microscopy, PEEM)成像了电子束加工的金纳米环样品的等离激元近场分布。利用双色的实验方法有效地打开了双色量子通道,从而导致发射电子的非线性阶次从3.80降低到1.85,并且光辐射电子的产额显著增加。通过近场PEEM图像表明,由于存在缺陷激发的强烈干扰,掩盖了结构的场分布信息。进一步分析缺陷位置处电子非线性阶次,发现纳米环缺陷位置处电子的非线性阶次下降程度显著低于非缺陷处。双色PEEM成像的技术对于等离激元近场成像等相关研究的发展起到推动作用。展开更多
1科学背景
光发射电子显微镜（Photoemission Electron Microscopy,PEEM）是一种对表面结构、电子态、化学反应等表面物理化学性质进行原位、动态研究的新技术，在化学、物理、材料等研究领域有着重要的应用。其工作原理是以紫外光或x...1科学背景
光发射电子显微镜（Photoemission Electron Microscopy,PEEM）是一种对表面结构、电子态、化学反应等表面物理化学性质进行原位、动态研究的新技术，在化学、物理、材料等研究领域有着重要的应用。其工作原理是以紫外光或x射线光来激发固体表面原子中的电子，采用电子光学系统记录光电子发射，并进行成像研究。展开更多
In reverse water gas shift （RWGS） reaction COa is converted to CO which in turn can be used to pro- duce beneficial chemicals such as methanol. In the present study, Mo/AlaO3, Fe/AlaO3 and Fe-Mo/Al2O3 catalysts were...In reverse water gas shift （RWGS） reaction COa is converted to CO which in turn can be used to pro- duce beneficial chemicals such as methanol. In the present study, Mo/AlaO3, Fe/AlaO3 and Fe-Mo/Al2O3 catalysts were synthesised using impregnation method. The structures of catalysts were studied using X-ray diffraction （XRD）, Brunauer-Emmett-Teller （BET） method, inductively coupled plasma atomic emission spectrometer （ICP-AES）, temperature programmed reduction （H2-TPR）, CO chemisorption, energy dispersive X-ray （EDX） and scanning electron microscopy （SEM） techniques. Kinetic properties of all catalysts were investigated in a batch re- actor for RWGS reaction. The results indicated that Mo existence in structure of Fe-Mo/AlzO3 catalyst enhances its activity as compared to Fe/AlaO3. This enhancement is probably due to better Fe dispersion and smaller particle size of Fe species. Stability test of Fe-Mo/AlzO3 catalyst was carried out in a fixed bed reactor and a high CO yield for 60 h of time on stream was demonstrated. Fez（MoO4）3 phase was found in the structures of fresh and used catalysts. TPR results also indicate that Fez（MoO4）3 phase has low reducibility, therefore the Fe2（MoO4）3 phase significantly inhibits the reduction of the remaining Fe oxides in the catalyst, resulted in high stability of Fe-Mo/Al2O3 catalyst. Overall, this study introduces Fe-Mo/Al2O3 as a novel catalyst with high CO yield, almost no by-products and fairly stable for RWGS reaction.展开更多
Novel organic-inorganic composite photocatalyst offers new opportunities in the practical applications of photocatalysis. Novel visible light-induced Cr-doped Sr Ti O3–carbon nitride intercalation compound(CNIC) comp...Novel organic-inorganic composite photocatalyst offers new opportunities in the practical applications of photocatalysis. Novel visible light-induced Cr-doped Sr Ti O3–carbon nitride intercalation compound(CNIC) composite photocatalysts were synthesized. The composite photocatalyst was characterized by X-ray diffraction(XRD), field-emission scanning electron microscopy(FESEM), high-resolution transmission electron microscopy(HRTEM), Fourier transform infrared(FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy, photoluminescence(PL) spectroscopy, and BET surface area analyzer. The photocatalytic oxidation ability of the novel composite photocatalyst was evaluated using methyl orange(MO) as a target pollutant. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading MO. For maximizing the photodegradation activity of the composite photocatalysts, the optimal CNIC content was determined. The improved photocatalytic activity of the as-prepared Cr-doped Sr Ti O3–CNIC composite photocatalyst may be attributed to the enhancement of photo-generated electron–hole separations at the interface.展开更多
Y2000-62088-1867 0010063全球定位系统用的10和2.45GHz 短基线干涉仪=10and 2.45GHz short baseline interferometers for position-ing systems[会,英]/Benlarbi—Delai,A.& Cousin,J.C.//1999 IEEE MTT-S International Microwav...Y2000-62088-1867 0010063全球定位系统用的10和2.45GHz 短基线干涉仪=10and 2.45GHz short baseline interferometers for position-ing systems[会,英]/Benlarbi—Delai,A.& Cousin,J.C.//1999 IEEE MTT-S International Microwave Sym-posium,Vol.4.—1867～1870(UC)展开更多
This paper expounds upon the basic principle of scanning electron microscopy(SEM),the main features of image types,and different signals,and the applications and prospects in earth sciences research are reviewed.High-...This paper expounds upon the basic principle of scanning electron microscopy(SEM),the main features of image types,and different signals,and the applications and prospects in earth sciences research are reviewed.High-resolution field emission SEM allows observation and investigation of a very fine micro area in situ.Using low-vacuum mode SEM,geological insulating samples can be analyzed directly without coating,demonstrating the wide application prospect.Combined with backscatter detector(BSE),energy dispersal X-ray spectroscopy(EDS),cathodoluminescence spectrometry(CL),and electron back-scattering diffraction(EBSD),SEM can yield multiple types of information about geological samples at the same time,such as superficial microstructure,CL analysis,BSE image,component analysis,and crystal structure features.In this paper,we use examples to discuss the geological application of SEM.We stress that we should not only focus on the CL image analysis,but strengthen CL spectrum analyses of minerals.These results will effectively reveal the mineral crystal lattice defects and trace element composition and can help to reconstruct mineral growth conditions precisely.展开更多
Because short pulse Nd:YAG laser of nanosecond pulse-width and high peak power has a unique capability to improve the mechanical properties of metal parts,a study on the development of high peak power short pulse from...Because short pulse Nd:YAG laser of nanosecond pulse-width and high peak power has a unique capability to improve the mechanical properties of metal parts,a study on the development of high peak power short pulse from Nd:YAG laser along with its peening application has been performed.The design scheme of laser and the characteristic of laser beam transmission are presented and discussed.A pulse energy of 25 J with 15 ns pulse-width and a maximum peak power of 1660 k W laser system which use one oscillation and eight amplifiers has been achieved.Laser beam has a max divergence angle of 0.03 mrad,a pulse-to-pulse pulse-width stability of±0.1 ns,and the pulse-to-pulse energy stability factors of less than±2.8%.A low value of divergence means an easier modification of a nearly hat-top laser beam intensity profile and an easier transmission of laser beam.To evaluate the performance of the laser system,several metal materials are processed.Laser peening quality and efficiency are analyzed by using an optical microscope,a transmission electron microscope,and an X-ray diffraction device.The processing results show that the performance of this laser system is excellent.展开更多
文摘本文利用双色–光发射电子显微镜(Photoemission Electron Microscopy, PEEM)成像了电子束加工的金纳米环样品的等离激元近场分布。利用双色的实验方法有效地打开了双色量子通道,从而导致发射电子的非线性阶次从3.80降低到1.85,并且光辐射电子的产额显著增加。通过近场PEEM图像表明,由于存在缺陷激发的强烈干扰,掩盖了结构的场分布信息。进一步分析缺陷位置处电子非线性阶次,发现纳米环缺陷位置处电子的非线性阶次下降程度显著低于非缺陷处。双色PEEM成像的技术对于等离激元近场成像等相关研究的发展起到推动作用。
文摘1科学背景
光发射电子显微镜（Photoemission Electron Microscopy,PEEM）是一种对表面结构、电子态、化学反应等表面物理化学性质进行原位、动态研究的新技术，在化学、物理、材料等研究领域有着重要的应用。其工作原理是以紫外光或x射线光来激发固体表面原子中的电子，采用电子光学系统记录光电子发射，并进行成像研究。
基金Supported by the Iranian Nano Technology Initiative Council and Petroleum University of Technology
文摘In reverse water gas shift （RWGS） reaction COa is converted to CO which in turn can be used to pro- duce beneficial chemicals such as methanol. In the present study, Mo/AlaO3, Fe/AlaO3 and Fe-Mo/Al2O3 catalysts were synthesised using impregnation method. The structures of catalysts were studied using X-ray diffraction （XRD）, Brunauer-Emmett-Teller （BET） method, inductively coupled plasma atomic emission spectrometer （ICP-AES）, temperature programmed reduction （H2-TPR）, CO chemisorption, energy dispersive X-ray （EDX） and scanning electron microscopy （SEM） techniques. Kinetic properties of all catalysts were investigated in a batch re- actor for RWGS reaction. The results indicated that Mo existence in structure of Fe-Mo/AlzO3 catalyst enhances its activity as compared to Fe/AlaO3. This enhancement is probably due to better Fe dispersion and smaller particle size of Fe species. Stability test of Fe-Mo/AlzO3 catalyst was carried out in a fixed bed reactor and a high CO yield for 60 h of time on stream was demonstrated. Fez（MoO4）3 phase was found in the structures of fresh and used catalysts. TPR results also indicate that Fez（MoO4）3 phase has low reducibility, therefore the Fe2（MoO4）3 phase significantly inhibits the reduction of the remaining Fe oxides in the catalyst, resulted in high stability of Fe-Mo/Al2O3 catalyst. Overall, this study introduces Fe-Mo/Al2O3 as a novel catalyst with high CO yield, almost no by-products and fairly stable for RWGS reaction.
基金Project(51208102)supported by the National Natural Science Foundation of China
文摘Novel organic-inorganic composite photocatalyst offers new opportunities in the practical applications of photocatalysis. Novel visible light-induced Cr-doped Sr Ti O3–carbon nitride intercalation compound(CNIC) composite photocatalysts were synthesized. The composite photocatalyst was characterized by X-ray diffraction(XRD), field-emission scanning electron microscopy(FESEM), high-resolution transmission electron microscopy(HRTEM), Fourier transform infrared(FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy, photoluminescence(PL) spectroscopy, and BET surface area analyzer. The photocatalytic oxidation ability of the novel composite photocatalyst was evaluated using methyl orange(MO) as a target pollutant. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading MO. For maximizing the photodegradation activity of the composite photocatalysts, the optimal CNIC content was determined. The improved photocatalytic activity of the as-prepared Cr-doped Sr Ti O3–CNIC composite photocatalyst may be attributed to the enhancement of photo-generated electron–hole separations at the interface.
基金supported by the National Natural Science Foundation of China(Grant No.41402031)
文摘This paper expounds upon the basic principle of scanning electron microscopy(SEM),the main features of image types,and different signals,and the applications and prospects in earth sciences research are reviewed.High-resolution field emission SEM allows observation and investigation of a very fine micro area in situ.Using low-vacuum mode SEM,geological insulating samples can be analyzed directly without coating,demonstrating the wide application prospect.Combined with backscatter detector(BSE),energy dispersal X-ray spectroscopy(EDS),cathodoluminescence spectrometry(CL),and electron back-scattering diffraction(EBSD),SEM can yield multiple types of information about geological samples at the same time,such as superficial microstructure,CL analysis,BSE image,component analysis,and crystal structure features.In this paper,we use examples to discuss the geological application of SEM.We stress that we should not only focus on the CL image analysis,but strengthen CL spectrum analyses of minerals.These results will effectively reveal the mineral crystal lattice defects and trace element composition and can help to reconstruct mineral growth conditions precisely.
基金supported by the National Hi-Tech Research and Development Program of China("863"Project)(Grant No.2012AA041310)
文摘Because short pulse Nd:YAG laser of nanosecond pulse-width and high peak power has a unique capability to improve the mechanical properties of metal parts,a study on the development of high peak power short pulse from Nd:YAG laser along with its peening application has been performed.The design scheme of laser and the characteristic of laser beam transmission are presented and discussed.A pulse energy of 25 J with 15 ns pulse-width and a maximum peak power of 1660 k W laser system which use one oscillation and eight amplifiers has been achieved.Laser beam has a max divergence angle of 0.03 mrad,a pulse-to-pulse pulse-width stability of±0.1 ns,and the pulse-to-pulse energy stability factors of less than±2.8%.A low value of divergence means an easier modification of a nearly hat-top laser beam intensity profile and an easier transmission of laser beam.To evaluate the performance of the laser system,several metal materials are processed.Laser peening quality and efficiency are analyzed by using an optical microscope,a transmission electron microscope,and an X-ray diffraction device.The processing results show that the performance of this laser system is excellent.
