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The time-of-flight mass spectra of carbon nanotube plasma produced by laser was first investigated in this paper. We found the hemi-spherical tips of carbon nanotube were easily fragmentated and aggregated into fullerenes between Coo arid C_(174) in high laser fluence. 相似文献
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二元以至多元原子簇(包括铝氧原子簇)的产生与研究是当前十分活跃的领域.最近,我们在自制的装置上,以功率密度达10~8W·cm~(-2)的脉冲激光束(波长532nm)在10_4~-Pa 的真空中溅射AlN 样品时,在实验记录的正负离子质谱中出现的几乎都是铝原子簇离子;而当我们选择α-Al_2O_3为样品时,则观察到了一系列质量分布很广的二元铝氧原子簇负离子,如图1所示.图1的飞行时间质谱是连续100次记录的数据叠加的结果,图中各Al_nO_m~-分别以(n,m) 相似文献
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Bismuth-containing semiconductor material is a hot topic in photocatalysts because of its effective absorption under the visible light.In this paper,we expect to explore a new bismuth-based photocatalyst by studying the subsolidus phase relations of the Bi2O3–Fe2O3–La2O3system.The X-ray diffraction data shows that in this ternary system the ternary compound does not exist,while seven binary compounds(including one solid solution series Bi1 xLaxO1.5with 0.167≤x≤0.339)are obtained and eight compatibility triangles are determined. 相似文献
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A single crystal of Li3Ba2Ho3(WO4)8 was obtained from a flux of Li2WO4 under an air atmosphere. The structure of the pure crystal was determined by single-crystal X-ray diffraction method. It crystallizes in the monoclinic system, space group C2/c with a = 5.240(4), b = 12.790(10), c = 19.247(15), β = 91.921(15)°, V = 1289.1(18)3, Z = 2, Mr = 2773.09, Dc = 7.144 g/cm3, μ = 47.732 mm-1, Rint = 0.0693, F(000) = 2340, the final R = 0.0472 and wR = 0.1221 for 1535 observed reflections (I > 2σ(I)). The Li3Ba2Ho3(WO4)8 has a high structure disorder with one 8f site shared by Li(1) and Ho ions with occupancy of 0.25 and 0.75, respectively. The fundamental structure is constituted by distorted square antiprisms Ho/Li(1)O8 with C1 symmetry, distorted Li(2)O6 octahedra and BaO10 polyhedra. The optical properties were investigated by IR and absorption spectroscopy, and the emission cross sections and gain cross sections of 5I7 → 5I8 of Ho3+ were calculated. 相似文献
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C6。可以说是迄今发现的具有最美妙对称性的分子——60个碳原子均位于完全等价的几何位置上,而且由于形成了覆盖整个‘咏’面的大。键,结构非常稳定.最近一系列实验发现,C。。在激光的作用下还能进一步聚合饲.我们在实验中首次发现了C。。在脉冲激光溅射下自聚成的负离子,并对实验记录的质谱作了分析.1实验实验在自制的激光等离子体源飞行时间质谱计问上进行.C。。粉末压紧后以n面胶固定在样品架上.实验所用的激光波长532urn,脉宽7us.会聚后作用于样品的激光功率密度在10’-10‘W·cm-’之间.激光产生的等离子体中的正负离… 相似文献
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对晶体生长机制、动力学与微结构衍化的认识是实现纳米材料的尺寸和形貌可控制备的基础.以表面溶解沉积为特征的奥斯特瓦尔德熟化(0R)理论常用来解释传统的晶体生长过程.在该生长模式下,纳米晶体的生长呈现出小颗粒溶解而大颗粒逐渐长大的特征.在纳米材料体系,近来还发现了一种重要的新的晶体生长模式——“取向接合(OA)”机制,在该机制下,两个晶格取向一致的初级纳米颗粒可通过直接接合和结构调整,从而长成一个新的晶体.这一机制已被证实在许多纳米材料体系中广泛存在,并对所合成的纳米材料的形貌、微结构具有非常显著的影响,在构筑新型纳米结构方面具有潜在的优势.本文我们首先回顾了OA生长机制的认识历程和这一机制对材料科学的重大意义;进而,基于我们的研究工作系统介绍了OA生长动力学模型的建立与发展,进一步阐述了这一机制的微观过程及其对材料内部缺陷的特殊影响,深入地分析和讨论了表面包裹的强弱、表面作用的性质对OR机制和OA机制的抑制和调控作用;基于上述表面包裹可调控纳米材料的生长机制的认识,我们结合近期研究结果,从动力学角度分析了量子点的生长机制与其发光特性的内在关联,阐明了表面包裹调控量子点的发光性质的本质原因,为制备不同发光特征的量子点及理解其发光性质衍化规律提供了重要的理论指引. 相似文献
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Bismuth-containing semiconductor material is a hot topic in photocatalysts because of its effective absorption under the visible light. In this paper, we expect to explore a new bismuth-based photocatalyst by studying the subsolidus phase relations of the Bi2O3-Fe2O3-La2O3 system. The X-ray diffraction data shows that in this ternary system the ternary compound does not exist, while seven binary compounds (including one solid solution series Bi1-xLaxO1.5 with 0.167 〈 x 〈 0.339) are obtained and eight compatibility triangles are determined. 相似文献
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The subsolidus phase relations of the ZnO-BaO-V2O5 ternary systems were investigated by means of X-ray diffraction analysis. There are three ternary compounds, nine binary compounds and sixteen 3-phase regions found in this system. The crystal structure of the ternary compound Ba2ZnV2O8 was refined by Rietveld profile fitting method and the powder diffraction pattern is given. A new ternary compound Ba3.4Zn0.8V4O14.2 has been found by the powder diffraction pattern. 相似文献