7817.com金沙娱乐

听写稿:

[编辑:永太净化设备经营部] [时间:2017-06-09]


听写稿:

So in order to answer this question, we are first to definewhat is the time scale of an electron in an atom. And for that, we can use themodel of a hydrogen atom by Bohr, where you see here a positively charged coreand an electron moving around this core. And to have an idea about the timescale of this electron moving around the core, we can calculate it with thisequation and we end up with a period time of about 100 of attosecond. So whatis an attosecond? An attosecond is about, is actually 10-18 second. Andto give you an idea about what an attosecond is compare to a second. Well, it’sexactly the same as comparing a second to the age of universe. So to accessthis information here of the motion of the electron, what we need is flash oflight extremely fast. And those flash of light are attosecond pulse train. In orderto obtain this attosecond pulse train, we use a process that is called highharmonic generation. That is based on the upconversion of a laser frequency intoits high harmonic. This way we obtain a common frequency that is very large spectrally,which means that in the time domain we obtain a train of an attosecond pulse. Now,what type of information we can get thanks to these pulses. Well, we canactually see electron motion in big, eh, system, like molecules. And we can seethe changes of the molecules and how those changes appear, basically howreaction, a chemical reaction, happen. And the other possibility is also tounderstand how damage in cells happen, because any damages in cells start by amotion of an electron…

翻译稿:

为了回答这个问题,我们首先要确定一个原子中电子(运动)的时间尺度,7817.com金沙娱乐。为此,我们使用波尔的氢原子模型。请看,在这个模型中,这里有一个带正电的核,一个电子绕着这个核运动。要想知道这个电子绕核运动的时间尺度,7817.com金沙娱乐,我们可以用这个公式计算,结果得到(运动)周期时间大约是100阿秒。那什么是阿秒呢,7817.com金沙娱乐?1阿秒大约是,实际上也就是10-18秒。这里给你一个用1阿秒与1秒相比较的概念:这就和用1秒跟宇宙的年龄(译者:大约可以折算出4.4×1017)相比较的感觉一模一样。为了获得这里电子运动的信息,我们需要闪动(频率)非常快的光。那种闪动(频率)非常快的光就是阿秒级的脉冲序列。为了获得这种阿秒级的脉冲序列,我们利用一种叫做高次谐波发生的方法。这种方法的基础是将一束激光的频率升频至它的高次谐波。这样一来,我们就可以得到一种光学频谱极高的共有频率;也就是说在一个时间域内,我们得到了一串阿秒脉冲。现在我们有了这些脉冲,我们能得到什么样的信息呢?我们能够真实地看到大的~嗯~系统中??比如分子中??的电子运动。我们还能看到分子的变化,看到那些变化是怎样发生的;大致说来就是反应??一个化学反应是怎样发生的。另外一种可能性是我们能了解细胞中的损伤是怎样发生的,因为细胞中的损伤都是从一个电子的运动开始的……