Ultrafast spectroscopy of quantum materials

量子材料的超快光谱

• 批准号: 238349-2006
• 负责人: Dodge, Steven
• 金额: $ 3.23万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2006
• 资助国家: 加拿大
• 起止时间: 2006-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=336554
• 关键词: Ultrafast; spectroscopy; quantum; materials

Your toaster gives your morning bread its crunch by passing electrical current through a coil of wire, causing the wire to become red hot and your bread a golden brown. The wire heats up because the electrons flowing through it flow imperfectly, bumping into microscopic imperfections in the metal as they move, transforming the electrical energy supplied by your outlet into heat energy. The same process is responsible for the much less desirable electrical losses found in power lines and computer chips. In typical metals, the average time that an electron travels freely before bumping into something is a few millionths of a billionth of one second, or a few femtoseconds. For a sense of the brevity of this unit of time, it takes about one hundred femtoseconds for a beam of light to travel the width of a human hair. The experiments funded by this research grant will help us to understand the processes that inhibit the flow of electrons in materials, by employing new technology to generate laser pulses with femtosecond duration. Since these pulses are comparable in length to the average time between electron collisions, they can be used to observe the motion of electrons in real time as they respond to an electrical impulse. Much in the way a movie camera reproduces motion with a series of still photographs separated by a thirtieth of a second, we can make a series of electrical measurements, using the laser pulses to limit the time of observation to a few femtoseconds. Armed with these ultrafast movies of electronic motion in solids, we will be able to improve our understanding of how different materials conduct electricity, and what factors limit that conduction. These studies are of considerable basic scientific interest, and Canadian researchers are known internationally for our contributions to knowledge in this area. Furthermore, the understanding provided by these studies may help us to engineer electronic materials for use in power lines, consumer electronics and electronic communications.

你的烤面包机使你的早餐面包发出嘎吱嘎吱的声音，它是通过电流穿过一卷电线，使电线变得红热，你的面包变成金棕色。电线变热是因为流经它的电子不完美地流动，当它们移动时撞到金属中的微观缺陷，将插座提供的电能转化为热能。同样的过程也是造成电力线和计算机芯片中不太理想的电力损失的原因。在典型的金属中，一个电子在碰撞到某个物体之前自由运动的平均时间是百万分之十亿分之一秒，或几飞秒。对于这个时间单位的短暂感，一束光传播人类头发的宽度大约需要100飞秒。这项研究资助的实验将帮助我们了解抑制材料中电子流动的过程，通过采用新技术产生飞秒持续时间的激光脉冲。由于这些脉冲的长度与电子碰撞之间的平均时间相当，因此它们可以用来观察电子响应电脉冲时的真实的运动。就像电影摄影机用一系列相隔三十分之一秒的静止照片再现运动一样，我们可以进行一系列电学测量，使用激光脉冲将观察时间限制在几飞秒内。有了这些固体中电子运动的超快电影，我们将能够提高我们对不同材料如何导电的理解，以及什么因素限制了这种导电。这些研究具有相当大的基础科学意义，加拿大研究人员因对这一领域知识的贡献而闻名国际。此外，这些研究提供的理解可能有助于我们设计用于电力线，消费电子和电子通信的电子材料。