So let's actually let you try another example of solving a problem that has to do with one of the spectrums.
下面请大家来看一下另一个例子,这次是一个需要大家解决的关于光谱的问题。
And in the end, when it's at equilibrium, and you look and you'd make a measurement, right, you could do spectroscopy.
当他处于平衡状态的时候,你可以做测量,比方说做光谱分析。
So, let's take a look at the different kinetic energies that would be observed in a spectrum for neon where we had this incident energy here.
那么,让我们来看一下,在已知入射能量的情况下,可以在氖光谱中观测到哪些不同的动能。
He measured the line spectra of atomic hydrogen.
测量了氢原子的线光谱。
We might be asked, for example, to determine what all of the different elements could be that would produce a spectrum that gave us 5 different lines.
那么我们会问,比如,有哪些不同的元素可以产生,一个有五条分立谱线的光谱?
And let's look at the final kinetic energy that we'd observe in this spectrum, which is 384 electron volts, so what is that third corresponding ionization energy?
然后让我们来看一下,在光谱中观测到的,最后一种动能,它大小是,384,电子伏,那么这相应的第三种电离能是多大?
So that's promising. We did, in fact, see red in our spectrum, and it turns out that that's exactly the wavelength that we see is that we're at 657 nanometers.
这是可能的,事实上,我们在光谱里看到过红色,结果它就是我们看到的在657纳米处的波长。
But if you look through your plate, and actually especially if you kind of look off to the side, hopefully you'll be able to see the individual lines of the spectrum.
你可以看到连续的光谱,但如果你们从片子里看,特别从周边看,你们能看到。
And so when we get to n equals three that would be m shell by the spectroscopists' notation.
当n等于3的时候,根据光谱学家的标记法,那就是第m层。
So, let's say we're looking at an element and we have an emission spectra, and we know that it has five distinct different kinetic energies in that spectrum.
比如我们正在研究一个元素,而且我们得到了它的光谱,知道了在它的光谱里,有五个分立的动能。
Can anyone not see it? Does anyone need -- actually I can't even tell if you raise your hand. So ask your neighbor if you can't see it and get one of the plates if you're having trouble seeing with the glasses. So this should match up with the spectrum that we saw.
有人没看到的吗?,有人需要-实际上你们举手我也看不见,看不到的话就问你们周围的人借个小片,如果你们用眼镜看不到的话,这应该和我们看到的光谱是吻合的。
Because only atomic hydrogen has that set of lines which means I could then take the spectra of gas phase species and use that information to identify.
我在这抬头看看然后离开,那就是氢原子,那就意味着,我可以测定,气相种类的光谱并且运用那个信息来鉴定。
Spectroscopy is how you go and look at patterns, not just individual lines.
光谱学就是你怎样运行和看待一个图案的,而不是单独的线条。
and he knew this the same way that we saw it in the last class, which is when we viewed the difference spectra coming out from the hydrogen, and we also did it for neon, but we saw in the hydrogen atom that it was very discreet energy levels that we could observe.
那就是,当我们看氢原子发出的光谱时,我们也看了氖气,但我们看到,氢原子能级是分立的,这些,在当时,已经被观察到了,他也都知道。
So that's why we're not seeing separate lines in this spectrum.
因此,我们在光谱中看不到,分立的谱线。
So, how many distinct, so again, we're talking about distinct kinetic energies, a spectrum for the element hafnium, 72 and I'll tell you here that it has a z of 72, so you don't have to spend two minutes searching your periodic table.
好,有多少分立的……还是一样,我们讨论的还是不同的动能,铪元素的光谱中出现,而且我来告诉大家铪的原子序数是,这样你就不用因为在元素周期表中找它,而花费两分钟的时间了。
And I also want to point out, it's guaranteed pretty much you may or may not be able to see, sometimes it's hard to see that one that's getting near the UV end of our visible spectrum. So we won't worry if we can't see that.
我要指出的是,我可以保证你们,但你们可能会看不到,有时候很难看到,这个可见光谱边缘接近紫外光地方的这根谱线,所以看不到也不用担心。
So, for example, when people, and we'll talk about this next class, were looking at different characteristics spectra of different atoms, what they were seeing is that it appeared to be these very discreet lines that were allowed or not allowed for the different atoms to emit, but they had no way to explain this using classical physics.
举个例子,当大家看到,不同原子的特征光谱时,他们看到的是一些分离的线,那可以使不同的原子,发射或不发射出去,但是这些无法用经典物理来解释。
S This is s. S, according to spectroscopy, 0 means that l equals zero.
这就是s的意义,在光谱学中,表示l等于。
So there are two electron configurations in the n equals one shell, if we follow according to the selection rules that we spelled out last day.
如果根据上次课,我们阐明的原子光谱选择定则,我们就会知道在n等于1的那一层,有两种电子图像构型。
Already from this class if I told you that I gave you energies in some spectrum but they were off by a factor of four, what would you think? Maybe the Z is wrong.
从这节课开始,如果我告诉你我给了你,在某些光谱里的能量,但它们不属于四大元素之一,你会怎么想?也许Z是错的。
We can plug this in further when we're talking about the visible part of the light spectrum, because we know that for n final equals 2, then that would mean we plug in 2 squared here, so what we get is 1 over 4.
当我们讨论可见光谱的时候,我们可以把这个代进去,因为我们知道n末是等于2的,这意味着我们可以。
You don't need to know those, but just because it's a special case with the hydrogen atom, they do tend to be named -- the most important, of course, tends to be the Balmer series because that's what we can actually see being emitted from the hydrogen atom.
你们不需要记住,但因为这是氢原子的特例,人们想要命名它,最重要的是当然是Balmer系,因为它是我们可以看到的,从氢原子放出来的光谱。
So these names, they don't really make any sense why they're called past s p and f, and it turns out that it comes from spectroscopy terms that are pre-quantum mechanics where, for example, this is called the sharp line, I think the principle, the diffuse, and the fundamental.
看到这些名字,你会发现,它们为什么叫s,p,f是没什么道理的,事实上,它们来源于,量子力学之前的光谱学中的术语,例如,它们分别叫做锐线,我认为是主线,漫射和基本。
First there was the observation by Michelson who back in the late 1880s had done very precise interferal metric measurements of the hydrogen lines and had observed that the 656 nanometer line 3 associated with the transition of n equals 3 to n equals 2 was, in fact, a doublet.
首先是麦克逊,在1880年底的观察,他以公制单位对氢原子的光谱线,作了准确的,无其他因素干扰的,测量,发现当n值由3变为2时,会同时得到波长为656纳米的谱线3,实际上是有两条线。
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