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中国科学院地质与地球物理研究所2013年度（第13届）学术年会

作者： Jinhua Li Kunpeng Ge Yongxin Pan Wyn Williams Qingsong Liu Huafeng Qin Paleomagnetism and Geochronology Laboratory Key Laboratory of Earth's Deep InteriorInstitute of Geology and GeophysicsChinese Academy of Sciences China-France Biomineralization and Nano-Structure Laboratory Chinese Academy of Sciences Paleomagnetism and Geochronology Laboratory Institute of Geology and GeophysicsChinese Academy of Sciences

[1]Single-domain magnetite particles produced by magnetotactic bacteria(magnetosomes) and aligned in chains are of great interest in the biosciences and ***,we investigated angular variation of magnetic properties of aligned Magnetospirillum magneticum AMB-1 cells,each of which contains one single fragmental chain of *** measurements at increasing angles from the chain direction,we observed that(i) the hysteresis loop gradually changes from nearly rectangular to a ramplike shape(e.g.,B and remanence decrease),(ii) the acquisition and demagnetization curves of IRM shift toward higher fields(e.g.,B increases),and(iii) the FORC diagram shifts toward higher coercivity fields (e.g.,B increases).For low-temperature results,compared to unoriented samples,the samples containing aligned chains have a much lower remanence loss of field-cooled(δ) and zero-field-cooled (δ) remanence upon warming through the Verwey transition,higherδ-ratio(δ=δ/δ) for the measurement parallel to the chain direction,and lowerδ-ratio,largerδ andδ values for the perpendicular *** simulations confirm the experimental observations and reveal that the magnetization reversal of magnetosome chain appears to be noncoherent at low angles and coherent at high *** simulations also demonstrate that the angular dependence of magnetic properties is related to the dispersion degree of individual chains,indicating that effects of anisotropy need to be accounted for when using rock magnetism to identify magnetosomes or magnetofossils once they have been preserved in aligned ***,this study experimentally demonstrates an empirical correspondence of the parameter B to B rather than B,at least for magnetite chains with strong shape *** suggests FORC analysis is a good discriminant of magnetofossils in sediments and rocks.

关键词： magnetosome chain magnetic property angular dependence magnetic anisotropy rock magnetism paleomagnetism.

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Mode splitting transmission effect of surface wave excitation through a metal hole array

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Light(Science & Applications) 2013年第1期2卷 192-196页

作者： Lin Chen Yiming Zhu Xiaofei Zang Bin Cai Zhou Li Le Xie Songlin Zhuang Engineering Research Center of Optical Instrument and System Ministry of EducationShanghai Key Lab of Modern Optical SystemUniversity of Shanghai for Science and TechnologyShanghai 200093China

The resonant frequencies of the excited surface waves on a metal hole array with respect to the incident angle were studied in the terahertz *** experimental and theoretical results demonstrate that the resonant peak of surface wave excitation splits into two when transmitted through a metal hole array *** high-order mode with resonant frequency above the cutoff frequency fc(plasma frequency effect)has a shorter attenuation length than that of the low-order mode whose resonant frequency is below *** reason is that the high-order mode is a coupled mode consisting of surface wave and hole modes,while the low-order mode is just an excited surface wave(which can be considered as the spoof surface plasmons).Our investigation may open a door to distinguish the spoof surface plasmons and the coupled modes of surface waves and hole modes.

关键词： angular dependence cutoff frequency metal hole arrays surface waves terahertz

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Alignment of Vertically Grown Carbon Nanostructures Studied by X-Ray Absorption Spectroscopy

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Materials Sciences and Applications 2014年第13期5卷 966-983页

作者： Jeannot Mane Mane Francois Le Normand Rolant Eba Medjo Costel Sorin Cojocaru Ovidiu Ersen Antoine Senger Carine Laffon Bridinette Thiodjio Sendja César Mbane Biouele Germain Hubert Ben-Bolie Pierre Owono Ateba Philippe Parent IPCMS UMR 7504 CNRSStrasbourgFrance Ecole Nationale Supérieure Polytechnique(National Advanced School of Engineering) Department of Mathematics and Physical SciencesThe University of YaoundéIYaoundeCameroon Physics Department Faculty of ScienceUniversity of YaoundéIYaoundeCameroon Physics Department Faculty of ScienceUniversity of DoualaDoualaCameroon LURE UMR CNRSCentre Universitaire Paris SudOrsayFrance

X-Ray Absorption Spectroscopy (XAS) on the carbon K edge of carbon nanostructures (nanotubes, nanofibers, nanowalls) is reported here. They are grown on plain SiO2 (8 nm thick)/Si(100) substrates by a Plasma and Hot Filaments-enhanced Catalytic Chemical Vapor Deposition (PE HF CCVD) process. The morphology and the nature of these carbon nanostructures are characterized by SEM, TEM and Raman spectroscopy. According to conditions of catalyst preparation and DC HF CCVD process, carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon nanowalls (CNWs), carbon nanoparticles (CNPs) with different orientation of the graphene plans or shells can be prepared. From the angular dependence of the incident light and geometrical morphology of the nanostructures, wide variations of the C K-edge intensity of the transitions to the empty π* and σ* states occur. A full lineshape analysis of the XAS spectra has been carried out using a home-made software, allowing estimating the relative proportion of π* and σ* transitions. A geometrical model of the angular dependence with the incidence angle of the light and the morphology of the carbon nanostructures is derived. With normalization to the HOPG (Highly Oriented Pyrolytic Graphite graphite) reference case, a degree of alignment can be extracted which is representative of the localized orientation of the graphitic carbon π bonds, accounting not only for the overall orientation, but also for local defects like impurities incorporation, structural defects ... This degree of alignment shows good agreement with SEM observations. Thus CNTs films display degrees of alignment around 50%, depending on the occurrence of defects in the course of the growth, whereas no special alignment can be detected with CNFs and CNPs, and a weak one (about 20%) is detected on CNWs.

关键词： X-Ray Absorption Spectroscopy Carbon Nanostructures(CNTs,CNFs,CNWs,CNPs) Plasma-and Hot Filaments-Enhanced Catalytic Chemical Vapor Deposition Geometrical Model angular dependence

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