原子直径

A cold atomic cloud with diameter 1.5mm and temperature≤150μK has been observed in MOT set up.

在磁光阱中观测到冷原子云，其直径为1.5mm，原子温度≤150μK。

Based on the theoretical calculation model for the structural information of metal melt, the main structural information, including relative concentration of active atoms, average diameter of the atomic clusters and the number of short-range atoms inside them, was achieved. Finally, by multiple non-linear fitting of experimental data, the function about viscosity and size of atomic clusters was established.

利用金属熔体结构信息的理论计算模型，得到该温度区间内铝熔体的主要结构信息，包括激活原子的相对浓度、原子集团的平均直径及其内部包含近程原子数等，最终通过实验数据的多次非线性拟合发现黏度与原子集团的尺寸之间存在函数关系。

The evaporation fields of metal atoms in the STM configuration have been calculated on the base of the binding energy of the atom on the tip, the total ionization energy of the atom, surface work function, the atomic radius and tip-sample distance.

本文的理论计算表明所需的外加电场强度决定于针尖原子的结合能，原子总的离化能，表面功函数，原子直径以及针尖和样品间距等。

In the single crystal of C60 with a FCC structure,positron mainly appears outside the C60 molecule.The main annihilation space is the interspace between molecules.The calculated positron bulk lifetime in C60 is 352ps, which agrees with experiment value of 356ps in literature.In carbon nanotube bundles with different dimeters,as the diameter of carbon nanotubes increases,the main space where positron appears changes from the interspace of carbon tubes to the space inside carbon tubes,the radio between positron annihilation with valence eletrons and core eletrons becomes larger,the positron bulk lifetime in carbon nanotube increase rapidly first and come to be a constant at the end.The calculated positron lifetime of carbon nanotube with a dimeter of 0.8～1.6ns is 332～470ps,which agrees with the experiment value of 394ps.Positron annihilation has been studied in widly used compound semiconductors.

计算结果表明：在片层结构的石墨晶体中，正电子主要在石墨层间的空隙中湮没，计算出的石墨中的正电子寿命为208 pS，与文献中的实验结果215 ps符合很好；在金刚石单晶中，正电子主要在碳原子之间的空隙中存在并发生湮没，计算出的金刚石中的正电子寿命为115 ps，文献中的实验结果110 ps左右符合；在面心立方结构的C60晶体中，正电子主要在C60分子球壳内外侧及分子之间存在，C60球形分子中心正电子分布很少，正电子的湮没区域集中在C60分子之间的空隙区域，计算出的C60中的正电子寿命为352 ps与文献中的实验结果356ps相符合；对于不同管径碳米管束中的正电子分布，随着碳纳米管直径的增加，碳纳米管束中的正电子由主要在碳纳米管管间的区域出现转变为主要在碳纳米管管内中心的区域出现：碳纳米管束中的正电子与碳原子的价电子的湮没概率变得越来越大，与核心电子的湮没概率变得越来越小；碳纳米管束中正电子的湮没寿命先迅速增大，而后趋于一定值。

Also, we can find that the diameter of carbon nanotubes affects the structure of Na nanowire obviously. In the carbon nanotube (4,4), the Na nanowire is monatomic linear strcture, while it is of helicity and larger diameter.

且碳纳米管的直径对纳米线的直径及结构有明显的影响，碳纳米管(4，4)中得到的纳米线为单原子排列的直线结构，而碳纳米管(6，6)中得到的纳米线则为直径较大的、带有一定螺旋性的线性结构。

Clusters are the agglomerates of a few to a few thousand atoms with relative stability and with a radius smaller than 50 nm.

团簇是由几个到几千个原子聚集形成的相对稳定的物质，直径小于50nm，是介于微观的原子和宏观的固体物质之间的新层状。

Since the atoms that make up normal,"solid" matter are mostly empty space, a star made almost entirely of tightly packed neutrons is extraordinarily dense: a fingernail's worth of a neutron star would have a mass of more than a trillion kilograms. A neutron star's density and gravity is second only to a black hole.

确切的说，是直径20km左右的一个超级中子，虽然不过只有一个大中型城市的体积，质量超过1.5倍太阳——译注）由原子组成的普通物质，其&实心&的物质内部其实绝大部分都是空的（大家完全可以用太阳系质量集中在太阳来想象原子内部，当然电子与行星有本质区别——译注），而一颗几乎全部由中子构成的恒星却密度极大：指甲大的一块中子星物质的质量达到万亿吨级，中子星的密度、引力仅次于黑洞。

Atomic emission spectrometry with spark discharge excitation was applied to the analysis of samples of stainless steel wires with diameter smaller than 8 mm.

火花激发原子发射光谱法应用于直径小于8 mm的不锈钢线材的分析，对此类试样应用了一种特制的夹具，用块状标准样品制作工作曲线。

In the United States, chronic alcoholism and hepatitis C are the most common ones.

在美国，慢性酒精中毒，肝炎是最常见的。

If you have any questions, you can contact me anytime.

如果有任何问题，你可以随时联系我。