Internal structure of Chinese scientists photographed water (fig) scientists | | | water _ shooting news
Water is the most common substances in everyday life. But the "water" the mystery of humans there are many problems yet to be solved. For example, we know from the junior high school textbook, which is made up of two hydrogen atoms and one oxygen atom, but what does water molecule looks like? How do they form a water molecule? Water is the source of life, its unique Hydrogen-bonded structure always make it difficult for scientists to explain. These are mysteries.
Recently, scientists in China – Beijing University Centre for quantum information, quantum materials science centre for collaborative innovation research group of Jiang Ying and Wang Enge group together make a big breakthrough in the field of water science, snaps a picture of the internal structure of a water molecule for the first time, allows direct water analysis in the experiment of hydrogen-bonding network configurations are possible. This scientific research on January 5 in full text form on a world authority on the scientific journal nature materials published online. Jiang Ying and Wang Enge were co-corresponding author of the article, doctoral student Karen Guo, Meng Xiangzhi Chen Ji is common the first author, xinzheng Li fellow at the school of physics, and Professor Shi Junren in theoretical aspects of quantum material Center provides important support and help. This work was supported by the National Council, Ministry of science and technology, the Ministry of education and Beijing University financing.
Water molecules taking pictures is not an easy thing
Water molecules taking pictures is not an easy job, because it is too small, only one hair of one out of 10,000, and in liquid case, water molecules move very fast. Pictures first challenge, is to select a suitable substrate.
Because of the filming equipment requirements, the conductive substrate. Yiqian, scientists General select of is to metal as lining end of, to water directly put in metal Shang for observation, but due to water molecular and metal Zhijian has is strong of mutual role, water molecular of track often will was metal of electronic State by flooded, so previously world States of scientists took to of water molecular photos, up just fuzzy of shape--"a no any internal structure of round raised". Chinese scientists selected metal surfaces insulating film (sodium chloride), taken as a substrate, water molecules adsorbed on the surface of the salt were observed, which greatly reduces the coupling between the water molecules and the substrate, so that water molecules intrinsic track structure is maintained.
Filming took an additional challenge of internal structures and signal strength of a single water molecule is unusually weak, very high precision of the experimental apparatus. Reporter understanding to, past 3 years, Jiang Ying topics group main is committed to super high tell of scan probe microscope system of development and development, in single molecular imaging and manipulation aspects accumulated has rich of experience, and made has series of research progress: in Asia nano scale on II dimension since Rotary lattice of Kondo effect for has real space imaging; detection to has single naphthalene phthalate cyanine molecular internal different of vibration mode of space distribution; on single features of molecular internal of chemical key achieved has selective manipulation. This based Shang, Jiang Ying topics group and ruler brother topics group close cooperation, through carefully of demonstration and tireless of exploration, success to put Asia molecular level tell imaging and manipulation technology application to water science area, groundbreaking to put scan tunnel microscope of tip as top gate, to picometers (1 skin m equivalent 1 m of one-zero) of precision control tip and water molecular Zhijian of distance and coupled strength, regulation water molecular of track State density in fee m level near of distribution, thereby greatly improve has imaging of letter noise than, Snap allows researchers to clearer water molecules look like. Water molecules based on high resolution images, the researchers can also determine further orientation of water molecules on the surface.
Possible to use and change the properties of water
In ordinary water, there are numerous water molecules. So, how did these water molecules together, we can see and touch the water? Chinese scientists when water molecules taking pictures, there have also been important discovery at this point. Previously, scientists already know that are connected by hydrogen bonds between the water molecules and the water molecules, hydrogen bonding configurations and directionality determines many of the characteristics of water. How to determine the Hydrogen-bonded network of water on micro-architecture is one of the key scientific issues of water science. If it snaps a picture of the internal structure of water molecules and spatial orientation, will allow direct water analysis in the experiment of hydrogen-bonding network configurations are possible, this is a lot of experimental scientists have dreamed about. Chinese scientists photographed not only the structure of a single molecule of water, also photographed the water clusters consisting of 4 water molecules through orbital images in high resolution micro hydrogen bonding of water clusters were first successfully resolved a configuration and found, through hydrogen bonds between the water molecules when connected, there is a certain degree of directionality. Combining first-principles calculation, researchers found that previously reported clusters of water molecules on the surface of the salt is not the most stable configuration, and offer a new four polymer adsorption structure.
Internal structure of the water molecule looks like, how to connect between the water molecules and the water molecules, they are in different solid surfaces, and how about a variety of changes, these research scientists, helps people use and change the properties of water, in real life, there is a wide range of applications.
Research Group of the relevant person in charge: for example, we are more concerned about the PM2.5, in essence it is a micron (1 micron is equivalent to 1 m of one out of 10,000) level of dust, as a kind of condensation nuclei in the atmosphere, outer surface usually wrapped with a layer of water. Uses above research work in the by development of water molecular high resolution imaging technology, if can put different type dust surface of this a layer water of micro structure resolved out words, will has may to environment scientists were some inspired and help, let they can remedy, pointed to take some chemical or physical of approach, enhanced dust outside steam of condensation, or promotion dust Zhijian of mutual aggregate, thereby makes PM2.5 dust can directly settlement to ground.
(Edit: SN098)
January 16, 2014 People's daily online-people's daily
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我国科学家拍摄到水分子内部结构(图)|科学家|水分子|拍摄_新闻资讯
水是人们日常生活中最常见的物质。但有关“水”的奥秘，人类还有很多问题没有解开。比如说，我们从初中课本上就知道，它是由两个氢原子和一个氧原子构成的，但水分子到底长什么样？它们又是如何形成水分子的？水是生命之源，其独特的氢键结构也一直让科学家难以解释。这些一直都是未解之谜。
日前，我国科学家——北京大学量子材料中心、量子物质科学协同创新中心的江颖课题组和王恩哥课题组共同在水科学领域取得重大突破，首次拍摄到了水分子的内部结构，使得在实验中直接解析水的氢键网络构型成为可能。这一科研成果已于1月5日以全文的形式在世界权威科学杂志《自然—材料学》上在线发表。江颖和王恩哥是文章的共同通讯作者，博士研究生郭静、孟祥志和陈基是文章的共同第一作者，物理学院的李新征研究员和量子材料中心的施均仁教授在理论方面提供了重要的支持和帮助。这项工作得到了国家基金委、科技部、教育部和北京大学的资助。
给水分子拍照不是一件容易的事儿
给水分子拍照不是一件容易的事，因为它实在是太小了，直径只有一根头发丝的百万分之一，而且在液态情况下，水分子运动非常快。拍照的第一个难题，就是给它选择一个合适的衬底。
由于拍摄仪器的要求，这个衬底还得能导电才行。以前，科学家一般选取的是以金属作为衬底，把水直接放在金属上进行观察，但由于水分子和金属之间有很强的相互作用，水分子的轨道往往会被金属的电子态所淹没，所以此前世界各国的科学家拍到的水分子照片，最多只是模糊的外形——“一个没有任何内部结构的圆形凸起”。这次我国科学家选取了金属表面生长的绝缘薄膜(氯化钠)作为拍摄的衬底，让水分子吸附在盐的表面进行观察，这大大减小了水分子和衬底之间的耦合，从而使水分子本征的轨道结构得以保留。
拍摄水分子内部结构的另外一个挑战，就是单个水分子的信号强度异常微弱，对实验仪器的精度要求非常高。记者了解到，过去3年，江颖课题组主要致力于超高分辨的扫描探针显微镜系统的研制和开发，在单分子成像和操控方面积累了丰富的经验，并取得了一系列的研究进展：在亚纳米尺度对二维自旋晶格的近藤效应进行了实空间成像；探测到了单个萘酞菁分子内部不同的振动模式的空间分布；对单个功能化分子内部的化学键实现了选择性操纵。在此基础上，江颖课题组和王恩哥课题组紧密合作，通过仔细的论证和不懈的探索，成功地把亚分子级分辨成像和操控技术应用到水科学领域，开创性地把扫描隧道显微镜的针尖作为顶栅极，以皮米(1皮米相当于1米的一万亿分之一)的精度控制针尖与水分子之间的距离和耦合强度，调控水分子的轨道态密度在费米能级附近的分布，从而大大提高了成像的信噪比，使得研究人员捕捉到水分子更清晰的面貌。基于高分辨率的水分子图像，研究人员还可以进一步确定水分子在表面上的取向。
利用和改变水的特性将成为可能
普普通通的一滴水中，就有无数个水分子。那么，这些水分子是怎么凑在一起，变成我们看得见摸得着的水呢？我国科学家给水分子拍照的时候，在这一点上也有重要的发现。此前，科学家们已经知道，水分子和水分子之间是由氢键相连的，氢键的构型和方向性决定了水的很多特性。如何在微观上确定水的氢键网络构型是水科学领域的关键科学问题之一。如果能拍摄到水分子的内部结构和空间取向，将使得在实验中直接解析水的氢键网络构型成为可能，这是很多实验科学家梦寐以求的事情。我国科学家不仅拍摄到单个水分子的结构，还拍到了由4个水分子组成的水团簇，通过高分辨率的轨道图像首次成功解析出了水团簇的微观氢键构型，并且发现，水分子之间通过氢键连接的时候，还存在着一定的方向性。结合第一性原理计算，研究人员发现以往报道的盐表面的水分子团簇都不是最稳定的构型，并提出了一种全新的四聚体吸附结构。
水分子内部结构长什么样，水分子和水分子之间如何连接，它们在不同的固体表面，又有怎样不同的变化，我国科学家开展的这些研究，都有助于人们利用和改变水的特性，在现实生活中有广泛的应用。
课题组相关负责人介绍：比如说大家现在比较关注的PM2.5，本质上它是一个微米(1微米相当于1米的一百万分之一)级的粉尘，作为大气中一种重要的凝结核，外表面通常会包裹着一层水。利用上述研究工作中所发展的水分子高分辨率成像技术，如果能够把不同类型粉尘表面的这一层水的微观结构解析出来的话，将有可能给环境科学家们一些启发和帮助，让他们能够对症下药，针对性地采取一些化学或物理的办法，增强粉尘外面水蒸气的凝结，或者促进粉尘之间的相互聚合，从而使得PM2.5粉尘能够直接沉降到地面。
（编辑：SN098）
2014年01月16日03:40
人民网-人民日报
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