Right, so now we go on. So, we know what this idea of when you have a nucleus that's spinning. And then you put in the magnetic field. And then it processes around that field. We're shown just one orientation there. But when you put a nucleus like, say, I equals a half. That's our proton. I = 1/2 for a proton. Then you have it in a magnetic field, it can have only two orientations. So here's your magnets, in the field, this is a proton, so it can orient that way. So you have to imagine, again, it spinning, here. So, it's spinning in that orientation. And it will fix just one orientation. I think the angle between the field, the field in this direction is about 54 degrees. So it will spin around in that direction. But it also has another orientation that it can spin around. It can also flip over, if you like, and it can spin in that direction. So again, it's precessing around. So what you've done [COUGH] is, when you put the magnetic field around the sample with protons in it, Is you've created two possible orientations for that magnet. The nuclear magnet. It can process this way with the field at an angle of 54. Or it can flip over and process against the field. Now, what you should be starting to understand is that There's gonna be a difference in energy between these two. This one is aligned with the field. That's gonna be a favorable way for the magnet to be. Whereas this one is aligned against the field, and that's going to be less favorable. What you're going to generate in terms of energy, you are going to have An energy gap, where you have one where it's going spin up. Up this way, is going to be lower energy. And the one down is going to be a higher energy. Okay, so that's what we have in all types of spectroscopy. We have a low energy level and we have a high energy level. And the idea then is to bring in some radiation, electromagnetic radiation. And if you match it exactly with that gap, then you flick it up to a higher energy state and you absorb the radiation. So the two, if you look at the two types we've looked at so far like UV and infrared. The molecule in the infrared is the vibrational modes for the molecule that are inherently in there and you just need to bring along the right frequency, and it'll cause transition. And anymore, if you don't have the magnetic field, then you can have your electromagnetic coming through, but it won't do anything. You need a magnetic field to generate the energy. Okay? And you generate the energy you gap because the [INAUDIBLE] behave like little magnets. And they have two orientations up for the protons and they have two orientations, up or down. And that will create an energy gap and then you put your electromagnetic radiation at a radio frequency field in there. It's enough to cause the transition. So you observe. That's the fundamentals of why you get in a spectrum for a proton. Right, so here we have a field direction or in the field direction again we have an animation here where they're spinning around. And as I say I equals a half, you have two orientations. So why two orientations? And again this is based on quantum theory, you got the full understanding. You got to accept it. You say, a particle with I=1/2 has two components and in a magnetic field they are split into +1/2 and -1/2. So, you can picture this again if the nucleus is spinning so the closer half is clockwise, spinning in a clockwise direction and the minus half is in an anticlockwise direction. Also, you'll see them referred as two states, alpha and beta. So similar to how you classify electrons. And again as we saw in the previous one, when you have an external magnetic field, one lines up with the field and the other will line up against the field and they will create that energy gap. So again, here is a simple representation so you have this processing, again it's you see this written in the textbooks quite a lot, but it's procession. You have to always remember that it's processing around, like that gyroscope, around the magnetic field. So the process was up, if we designate plus a half. And that's the lower energy orientation. The spin is aligned with the magnetic field, but it will also process with where it's against the magnetic field. And we call that beta or. That will be a higher energy state. So in a more transitions for protons, we're basically bringing in our lower energy, this is a higher energy. We're bringing in the electromagnetic radiation to induce a transition between these. That's what all we observed. What we've talked about is a proton, we said it has, we look back, that has I = 1/2 spin, 1/2. But for Deuterium 2H you have I equals 1, and you have three components. So you have three possible orientations for that nucleus with the magnetic field. You have plus 1, 0, or minus 1, so you produce three orientations in space. So here you have the proton one we've talked about. But now for Deuterium I equals 1, you have three. You have one where it's in line with the field, and then you have one where it's perpendicular to the field, and then you have one where it's opposing the fied. Right, so this precession is quite important, because it says there, the spin axis will rotate around the direction of the field like a gyroscope, and we said the angle is always the same, it's about 54. So here it is here, so you have the precession. This is the plus half component. This is where it's lined up with the field. And we call this the Larmor precession, as you can see hear that we have I think it's given. So we call this the Larmor precession frequencies. Frequency of precession is called omega zero. And as we know this is proportional to the field. We define the field to make any field that we apply B0. So these are portional to the field will B0, and then the portionally constant is given by gamma, which is called the magnetic gyro. It's the magnetogyric ratio all. So this then is a different value for each nucleus. You have a value for the proton, 1H, you've got a different value for the and a different value for. So the precession frequency is proportional to the magnetic field. So sometimes, again, what you'll see in textbooks is you'll see this kind of orientation here. Spin up and spin down, where it's like a fixed magnet. Here you have the external magnetic field. Here's your plus a half, here's your minus a half. Always important to know around here around the magnetic field it's not like a barrier magnetic it's actually processing the frequency and the frequency by which it processes is given by Omega 0. And when we want to change this, what we do in a mass spectroscopy is it's rotating around like this. When we want to change it, we need to bring in Electromagnetic radiation that has this frequency. You can see this is going around in a circle, you can define this in terms of number of cycles per second. Or radiance per second, angles. Degrees per second, and you need to then flip it over, you need to bring in a frequency that has exactly that frequency. When that frequency is brought in at the right angle, it will slip it over. So you go from low energy state to a high energy state. And you'll see a peak, and that's where the resonance, cuz it's in The input frequency has to be in resonance with that. So you can see how we set this gamma is different for each nuclei. So, you can see for a proton it will have a certain value. Now for carbon 13, there's something like that would often absorb much smaller. So, for the same magnetic field this procession frequency will be much smaller for carbon. So, that means you'll need, it'll have resonance or you'll have an absorption at a much lower frequency then.
