 Prometar, ki so več similačne, tako da ne zelo všeč v skreče. OK. Čekaj, da smo počučili vse projekte. Proste, da imam nekaj par. Kaj je to? Nekaj par. Mislim, je to. Tako. OK. Tako, to je tukaj projekto. Zdaj sem potrebno replizirati spektrum. Zdaj se zelo spektrum. Zdaj sem tukaj, da je tukaj. Tako, nekaj nekaj spektrum. Zdaj se na toga. 8, 14, 0, 0, 5 in tako. Kaj je to? To je naloj. To je naval bras. To je nist standart. Zdaj se se drugi? Tako, nekaj. So začre. Zdaj, dobe. To je prej v vrc. Je to nekaj. To je replizirati spektrum. Zdaj, ga se videl. Zdaj, ga se vrc. Ni no. Ne razgleda nekaj otroj konstituenci. Ale je to vse delne, testovatejne pravi. Alojče zelo novi, ker ne zelo zelo in vzivni komponent in bilo se otevno delo, zato nekaj oxide in tukaj karbon vzivni komponent v zelo, zelo prišlo početno. Menešovali im through this in in in every cycle of pixel even before and after, because we do sort of quality assurance that some detector does not skip somewhere or something like this. Ok, so now we have uploaded spectrum. And now, for example, the next step is, if you don't, if you didn't do it yet, you can go and make energy calibration. Zdaj. Kaj smo videli? Zdaj smo prišli vzumati. Vzumajte. Zdaj smo videli. Vzumajte. Vzumajte. Vzumajte. Vzumajte. Vzumajte. Vzumajte. Vzumajte. Vzumajte. 8.04 kv. So I begin with calibration. So I begin with calibration. Hopefully I will do it reasonably. Hopefully I will do it reasonably. Let's click it, and I put here 8.04 energy in kv. Let's click it, and I put here 8.04 energy in kv. Okay, and then you see it here. We see it. Human brain see it. That's thin. You see thin k alpha. I'm afraid that for goopics it will not be enough statistics, but we can use it at least as a calibration point. This is now I have some 25.27. 27. These are the values taken from the file I was struggling before to show you. You have it online. Okay. Now the calibration is done. Now comes a pain. In goopics you must go through all these steps. First, you should define whether it's a trace element solution in a known matrix. We are using this, for example. You have a plant material homogenized matrix is cellulosis, and you are looking for PPMs of zinc in it, for example. That's trace element in known matrix. Here we don't know anything. We just know it's alloy, and we need to do that iteration. I was also mentioning at the beginning of my talk. Computer needs to assume matrix, calculate concentration, and then correct the matrix and do again. And once it converges, it will stop automatically. Okay, so iterative matrix solution. Setup. We measure this at 45 degrees. Protons 3.03 mv. This is the charge. I will show you next lecture how we measure the charge on a micro probe. So we know the charge quite well. And then we need to select the detector. As I mentioned to you, somebody should already describe the detector in your lab for you or you did it by yourself. It will take you quite some time. Measure all the thin standards. So this is the description. That's how you describe one detector after another, several of them in each lab. And usually we like to have them in hand for all the detectors. See, there are many of them. Sili, even SDD that I was showing you on a picture. So, for us, this was EGAR detector. Okay, it's already there. Everything is there in description. So, now we go sample. Sample structure I mentioned to you. You can have thin samples in pixel, no stopping, no absorption, easy life. You can have thick samples, a lot of integration for a software. And you can have even more complicated intermediate thickness where you need to do that integration from one energy to another. In our case, it's easy life. It's a tick target. You click there, tick target. Where is now? Oh, I have... Houston, we have a problem. I cannot reach OK button. Okay. So, now we will say, you see trace element solution is blank. Because I said it's iterative. But I can define fit elements for iterative solution. And I add. We know it's brass. Copper, zinc. They mentioned that there may be some iron in it. There is probably some tin in it, whatever. I can do a bit more than required. It's not problem. I will show me that there is no, I don't say, let's say no titanium in it. Okay. That's roughly, and let's try if he is able to fit with this set of peaks. Okay. And you see here at the bottom, this is to spoil somebody. Normalize concentration to 100% total. If you use this, it's just that you don't know how to integrate the charge. How to measure number of primary protons on your sample. If you're using this option, I know many people do for alloys that simply means that they don't measure the proton current. For alloys where you see everything in it, it works like this Naval brass. For first stainless steel, they will be providing you professional pride to measure the current on your sample. For example, stainless steel, let's say it has 7% of carbon in it. You will not see it. So you will provide completely wrong numbers because you will have, you will see, say, okay, I have just iron and some nickel and some manganese in it, and you will give wrong answer to your user. If you will measure the current, you will see that you don't see something in this sample. You will have a deficit of 7 mass percent, and you know it's an invisible component in stainless steel is, for example, carbon. And you will provide them good answer. That's a big difference. Okay. So in brass, there is no invisible elements here. I don't need to guess anything. And now let's do some spectrum details. I have already calibrated it. I can also see it in channel numbers. And I don't want to fit here at the edge where this our absorber kills the low energy part, and we don't need to fit up here because there's nothing. So I would say between 200 and 1200. Let's see now. Fit spectrum details see from 200. Oh, let's say 1200. Okay. Calibration, we already calibrated. So Goop is already calibrated our detector. We did it at the beginning. Then these are just default values, how much pile ups he will filter and he will take into account and so on. That's already there usually. And you say just okay. And now with a bit of luck we will be able to run. See now iteration after iteration. Let's see what we got. Here residual. Do you like it or not? What's wrong? Immediately you see I like that most of the time I have very low residual. But here something's wrong. I screw it up. What's going on? I mentioned to you Igla detector from Orteg that we are dealing with has nickel collimator. So instead of you should not use entire crystal but you need to reduce a bit the window because on the edges resolution is degraded. So they put nickel collimator in it and they didn't tell us. It took us long time to figure out why our nickel results are usually wrong. Simply if you have a lot of zinc zinc photons have roughly 9 kev when they hit the collimator they fluorescent with nickel ke alpha further down into the crystal. So you have artificial yield of nickel. Even nickel is not in your target but there is for example zinc in your target. How you solve this in how you solve this in goopics you say do another fit and now description of the sample we define and we add additional element and we say yes nickel but I don't need PPMs of this bastard this is parasit and I tell him I don't like him, it's parasitic element there. So it will be fitted but not taken into account in calculation of concentrations. OK OK, let's see if I didn't forget something if I will be able to run again. OK Is it much better now? It is, yes. And let's see what is our so this is what needs the data that they give you for this these are mass persons and let's see what we got let's see we got 62 percent for copper 38.9 for zinc what you say it's good or bad you don't like it I'm not how you see we didn't miss much see let's see here the concentrations 62 percent and 39 percent 38.9 we have like half of the a bit of iron and we don't have enough statistics to see tin that's the story with a bit of low statistics you will not get much better precision with pixie but it's not too bad if you are chemist you will say that's crap I push on a button and it gives me result to the 4 digit and you tell me that you are here you are missing here concentration bar 1 percent that's crap the problem is that they have no clue what their machine is doing and properly is doing 10 percent error and they always do it the same way and that's it but here we control everything from the beginning to start and we end up with 1 percent and for me as a physicist this is not a bad measuring result you must be critical to the devices you are buying cause the black boxes otherwise you will sometimes do the errors others did it for you so this is not a bad result but I am quite confident with it if we miss 1 percent always I would jump to the ceiling that's my personal approach to this ok gu pixie is a bit strange as you saw but that's probably the best we have for broad beam pixie at the moment in hands and it turned out that we will leave with it with a bit of efforts ok another 5 minutes and then we go very short through rbs yes please questions that's a problem we have 2 detector pixie we have also another detector there for low energies which also sees that energy you must be careful if there is no zinc for example or something heavy like I don't know with 10, 11 kV or something in your eglet will give you a right number because there will be not enough energy to excite nickel in your sample but if you have a lot of copper and zinc in it you are on a bad track you should use it as a parasitic and you will not evaluate nickel with this detector the value is when we were high school students we were joking that when we were doing practical exercises we got exact results for example, Millikan exercise if you know when you measure elemental charge some of my school friends got perfect results almost for a Nobel prize and we were joking that they were using a constant not a constant but it's a value of all the parameters in your experiment in order to yield the proper result this is roughly h value in Goopis is similar thing if you don't go in detail with these thin films into your efficiency calibration and you will take a standard like this and you will get instead of 61 54% of copper you know you have a problem but using that h value properly you can bring it to proper value so you solve it for copper and then if you have enough standards but not micrometer ones you don't care much about efficiency but you do h value which is also energy dependent and in the end if you do a lot of standards you may end up with similar precision as we did that's why h is there because efficiency calibration is not always very successful or people don't take time it's a lot of work they take for example one of the glasses needs standards that gives you 15 elements in one shot and you simply forget about the efficiency of detector you can even click in Goopis that he will ignore efficiency and he takes only h value it's a function of energy and your concentrations will be again correct and you can do it in one shot but if you have time I would rather suggest to measure efficiency correctly now we have on micro probe we have stainless steel and that's why we need to play quite sometimes with additional plastic collimation to reduce the yield from the wall of the chamber it's not so straightforward so one thing you can do it that you sacrifice a bit of solid angle and recess a bit more your sensitive crystal and then you see just really limited part of your chamber it's a problem always if you have stainless steel chambers it's another question yeah especially with glasses with glasses is usually everything for example in glass is oxide and for me that glasses are quite I never worked with them but I see colleagues it's a big art to put proper oxide see inside that your concentrations fit actually what I learned everything in glass is in oxide form and you need to tell goopics that everything is in oxide and then still concentrations are well calculated I do much more trace element calculation for plant or animal biology you know some matrices that are good description and you just work in a trace element and this works quite well and quite insensitive if you screw it up with a little bit of light element matrix your result is in such constraints as we saw it matrix is if everything is of light element sometimes we say if you put mylar as a matrix of cellulosis doesn't matter if you want 10% precision you will be inside absorption is quite similar trace element levels for example for zinc we can do 0.2 ppm in long-run up to concentrations that are 0.1% you can still consider everything as a trace for example you buy package of wheat flour and it's inside it's some zinc, some iron in very low concentration that are typical traces for diet if you don't get that zinc and iron you know and that's where we are very strong with pixie if it's 200 ppm in plant matrix we can measure it pretty well yes please in synchrotron you have fluorescence which is in the best beam lines you have better lateral resolution than we have there for example you take 5 kV 5 kV energy and you can do fantastically everything below rate and you can do fantastically everything below rate say 4.5 below the edge but you don't get information for example on tin on some copper on zinc so it's I say we are still in job because we are easily accessible much easier than the synchrotrons we are much cheaper and in some occasions not worse than day but I agree for example one good beam line on synchrotron costs about 10 million or even more our entire center you will see tomorrow there is about 5 or 6 million of equipment so these are different proportions there are just one beam line is much more worth than if we work in accelerator centers then our accelerator centers that's the reason if not let's do a quick tour on RBS for half an hour I know that you heard about it and I will again Natko would you remind me 10 minutes to 4 to stop whatever I did to do one seminar run together with you ok he was in CC in the email she was in CC she was in CC ok because I checked it online I couldn't find it I went to his webpage let's do really experimental view on RBS so you heard about rather for backscattering already and we will go fast through it especially some considerations of see that not yet oh ok so I will just tell you just few brief words and then I will go to experimental setups how you put together a reasonable system that evaluation we will try one for example and that's it as you know this is RBS is like playing with balls you throw something in the box of balls with different sizes and another ball a small one and you get a jump out and based on the velocity of recalled ball you can somehow deduce that's roughly the case so you are firing on your thin film sample or bulk sample or whatever with something light in our case we are using a lot of helium free because it's also we get also NRA signal and also we did in the past a lot with lithium ions but also with helium 4 projectiles for conventional rather for backscattering and then you put your detector on backscattered angle with some slits to define well the space solid angle and that's it how to connect it and so on I will show you a bit later so you have a complementary method you can take heavy particle light elements out that's elastic recall detection but we will limit to RBS so standard RBS we detect scattered ions with silicon detectors what kind of detectors I have something with me I try to not really open it they are old and used take them out please and show to the people ok surface barrier detectors where in the past when I did my diploma work I used surface barrier detector they are still in use and in sale only I remember that putting it into operation was huge stress you touch it you kill it like beryllium window on X-ray detector very difficult to wash once you touch with a finger forget throw it away will never work again in plenty detectors that are we using the silver one that goes around they are quite resistant you can even wash in isopropyl alcohol and you will recover all the properties so for the energy resolution full width of half maximum of americium alpha source the line has 5.8 mv so easy and by very weak alpha source americium very thin so and then you just put it in and measure what is the performance of your detector as I mentioned to your surface barrier detectors were very scratch sensitive that actually these silicon detectors are like anization chambers what you have part of the space volume where you don't when the ionization particle enters this volume you need to take care of that recombination once the free carriers of charge are formed you should prevent against recombination and you can do it in various ways on ionization chamber you usually put electric field that pulls charge particles to the electrodes here it simply very similar in the case of surface barrier detector your short key contact between metal and silicon does electrical field and pushes the carriers to the contacts and if in the last time implanted detectors you do similar thing but you implant ions and you form this transition layer that collects and pushes the charges to your collection electrodes you see this is again this is from Leo old book that I recommend all if you find it in some antique store keep it on your shelf because lot of things are still completely the same today as they used to be in my student times so you see this is when you put into contact metal and semiconductor you got so called short key contact and this is the electrical field inside depletion we call it depletion layer and if you go with charge particle through it here no charge will remain here but they will be simply one side and go to one side one and another and you record on the contacts pulse that's how they are encapsulated at the end this is Ortec drawing and you can see them they are going around how they look like okay that's an old excuse me they didn't mention maybe intentional maybe a little later they are different detectors sorry they are typically I don't know maybe the contact is 10 nanometer gold one on surface barrier detector I'm guessing something like this and probably that layer on surface barrier is slightly bigger than on implanted one yeah okay so if you go to all Ortec catalog how they describe how you connect so first you need to put their preamp and you plug to the preamp by a supply and then you go through analog spectroscopy amplifier and then multi channel analyzer today we still use this approach but we have one shortcut you can take the cable from here and go directly to digital pulse processor that's in the recent times much more common and good practice rules if you want to get really good resolution in rbs please when you will put things together try to remember connection detector preamplifier as short as possible once you go for example from chamber if you have preamp on the air site how you will do the connection I'm sending you several feed trus here and please think which one would fulfill the request that I told you the best out of those four so what is there coaxial cable that connects detector and your preamp has a property that it's called impedance and you should not interrupt it on this way what is interruption for example you go just with a normal wire for real detector to the inner vacuum electrical feature it's uncontrolled impedance of that part you will catch a lot of noise on that road so the best is you put coaxial cable of this type on your detector and this is already 50 ohm impedance and then you have coaxial connector on the vacuum site and then connect to one of those flanges and you have again coaxial connector on other side so you don't interrupt this 50 ohm logic this is also cable, please pass around that's also important and this is another thing the same holds for pixel detector your vacuum chambers are actually big chunks of metal and your shield on the coaxial cables when you bring it out of the chamber should not come into contact with it so one of the one of the flanges there fulfills this requirement please think which one is the best out of those four that's a task for you so don't come into contact with your chamber at all the earth definition of your detector should be done either by your digital pulse processor or your spec amp, not by your chamber coaxial shield on coaxial cable should never come into contact with your chamber if the cables from preamp to spectroscopy amplifier are quite long try to use preamp with higher gain historically we were using I will show you this normal preamp this is cambera model you have also ortec equivalent and their gains are actually quite low and we were buying new detectors but it was a big struggle to get like 11 kV then in rbs in the last time you see how we make it this is the interruption between the chamber and the earthing defined by these shields of coaxial cables even to the preamp from the spec amp 5 meters away in your rack as soon as we got some omic contacts over resolution goes from I don't know from 10 to 18 kilo electron volts so it's bad try to avoid it need not constant for this is not the best I will show you even better solution here you have lemo fit through if you know this one but here you see there is a problem you have conflict flange and you have a chamber there we usually put viton gaskets are around substitute for a copper gasket they are also in one of these enclosures and we insulate the screws so the flange is on a potential of your preamp and digital pulse processor along the way no contact with the chamber and then this is inside that's how it looks like you have some holders for your detectors they should not be in contact with you you have them usually in some insulating ceramic or plastic enclosures if you want to have mass resolution put your detector as close as 180° if possible 170° is quite standard angle for many laps and then if you have this thin americium source you measure this spectra this is logarithmic scale actually on linear you see only one peak and you check his full vit f half maximum if it's 11 and cambera tells you it's 11, you did a good job in our lap this was a bit struggle it's really difficult to put it in real conditions and have 11 kV until we didn't get in the lap first cool fat preamps from amptech now this is quite standard for example this is now silicon edge and you see both silicon isotopes here this if you want to fit in an array it's better if you take 10 kV for the resolution than the specs 11, so if you do it well you can sometimes even surpass the factory given resolution because they always do it on a safe side, they put it a bit more otherwise you would complain I cannot get it from you if you do RBS of course and if you do peaks I mentioned before measurement of incoming kind dose you have several approaches the easiest one many of us are using is you connect your sample through the charge integrator to the earth yeah thanks so if you want that this works that secondary electrons wouldn't escape please use some battery pack it is above at least 100 volts or more so that all secondary electrons would come back you can insulate entire chamber also works in some cases but it's a big antenna our charge digitizer doesn't like it sometimes there is always some straight current measure and then you have in bin devices when I was your age I got agent EIA practice in Rosendorf in 95 all the chambers had choppers that I am using in my case as well in the labs so I will share so they are insensitive these in bin devices to secondary electrons escape from the sample type of the sample they don't care if the sample is insulating or not and I will show you two types one is quite simple you have two cylinders and you put inside a mesh looking from a side with roughly four lines per millimeter and the beam is coming like 20% of the beam end up on the mesh and you put it to the charge integrator also on the mesh you get secondary electron escape and you put these two cylinders here on minus like 500 volts and you have very stable in bin charge integration you don't care what's on your sample you will always tell correctly how much beam goes to your sample and alternative which we are using on micro probe you rotate such chopper in your beam and you then integrate the backscattered signal gold peak in your EBS ok no, just for broad beam the chopper is appropriate for micro probe ok now when you do when you start RBS you must do an energy calibration based on what you get on the surface of your sample so because scattering edge of your scattering box in your spectra is simply multiplication of quantity called kinematic factor just function of both masses and angle and depends on initial energy if you know initial energy you know your element and the angle you know what should be the energy there on the edge of the box and then you take for example tantalum, rhodium, molybden, tital, silica, oxygen and you check what were the channels on the boxes and you calculate what the energy should be there if you did it correctly usually calibrations are quite linear in this case you see it was energy you calculated as 11.5 kV per channel times the number of channel plus 21.8 kV that's connected to the question natko what this offset here means each detector has small dead layer and thicker the dead layer thicker this linear larger this linear offset is let's see the one example is for example nitrite tantalum nitrite what you can do with RBS you can estimate both thickness geometry of the film this is the tantalum box and here is the substrate front edge here indicates that you have tantalum there if you check what is the energy here of these channels you know that it's tantalum box this this box belongs to elemental tantalum and if you have charge normalized measurements of nitrogen in your layer these boxes correspondingly lower and now depending on the thickness these boxes can be wider or narrower that's how you estimate then the thickness I will show you now a short example with cement array on these aluminum oxynitrite films we did a long time ago with the assistance of the agency in 2005 let me see if we will manage to ok so that's similar oh shit let me try to better yes thanks ok so this is cement array in myer from garhink and once you upload the spectra you can see here you can use read spectrum data ask just two columns channel and yield very simple so once you upload the spectra here it's name you go to set up and you say experiment you select the ion in our case lithium 7 and here is its energy angles and calibration the calibration I showed you how it's done just before and then this detector resolution for lithium always worse than for helium that's how the physics works and that's most of it you describe your experiment and then you need to input the target what was the structure there on the top they put gold then comes aluminum oxy nitrate we don't know this how much any of those is with ordinary rbs it will be a big pain we cannot separate whether it's oxygen atom or nitrogen atom this is beyond the ability and then they put here a tantalum and then etched silicon we can say that there is no much oxide here in silicon now let's see what we can do with with lithium with 4.2 mv now I'm already putting the tentative answers for gold the units are 10 to 15 atoms per square centimeter you have somewhere up here tool to recalculate what is the thickness in nanometers for gold then comes aluminum oxy nitrate this is one of the gases I put some for nitrogen roughly 1, 1, 1 we will see how good description will be this for the first iteration and then next tantalum is there and then next with finite thickness and then you put silicon with some great number that means silicon substrate let's see the calculation he will ask me for cross sections I say take everything rather fourth yes yes no no it's okay okay so I deliberately put here logarithmic scale if we put here linear doesn't look too bad our first guess you see what's worrying is this what the hell are these boxes here these box and these box if you put logarithm axis you can see it much more pronounced something's wrong our task is to understand what was that because they need to make these films and conditions are not always optimal you see they made it quite nice because we have two markers before and after the layer so roughly that distance between these two layers roughly indicates the thickness of the sample and you see this box roughly corresponds to this and this strange box similarly there is something actually in this layer here in between let us guess what is there we go to target we keep the golden layer as it is and we will add two more elements in this box something is wrong in these layers now gases when you do thin films what could be in let's try iron let's the iron is maybe for the lower box and what we will say for the higher box something heavier what would you say some gas doesn't matter nickel is almost iron I would take something further up I borrowed a periodic system from my daughter so natko said iron let's say the iron is for a lower box let's take something heavier maybe some rhodium palladium, silver maybe something let's say rutenium I don't know what did they have in this reactor what happened, what's going on there we will see what are our gases and we will put there not much, these are impurities in the thin film let's say 2% 2% 2 atomic percent and now if I say ok, he will complain see Menere is a picky guy he wants 100% you see so I will simply take a bit of oxygen away and now it should be ok and let's calculate again we will see what was our gas the heavier is not heavy enough the lighter is not light enough is it this box should be a bit more here and this box should be more here ok, let's try let's try tungsten I wouldn't say tungsten natko because you have a valley there in between gold it's too close but let's try to see something lighter than iron how far down you would go so iron is there we go down the road where we will stop your gases where would you go let's do scandium ok then let's go lower guys sorry iron should be tungsten let's go less than tungsten ok let's go to what silver for example or ruthenium yes, ruthenium and here we said we will use titanium or what no, for the lower one titanium ok let's do scandium ok and then we say calculate better gas but still far away so let me we don't have much time so the guys who are operating these facilities usually use for as a carrying gases gas what, something that chemically does not interact let's say argon for the lighter one so instead of scandium we say argon and what we will use for the heavier one from the same class let's try Xenon, yeah you see these are noble gases so for us all I was so shocked when one finds out that noble gases are stable in the film and now you can only play with a bit of concentrations and you will completely reconstruct and the story is not over but we will stop here you see this peak here and you see this peak here again and their separation their peaks and their separation is the width of the box what would you say so this and this obviously somebody was cheating with gold it was not pure gold and also tantalong was not completely pure turns out the best goasis silver, like 10% of silver in golden layer and some strange thing I don't even remember in next to tantal that's how you iterate the height of the boxes you will do just by changing the concentration I will try to maybe I have the last let's see if it's the correct one roughly like this without surface without these two peaks that's all of it sorry for taking you 5 minutes just one question