Unboxing a $1.5m Microscope - Sixty Symbols

really exciting day today we're expecting delivery of a high magnetic field stm fm that also goes down to temperatures about a factor of 10 and temperatures we've we've been able to achieve here previously it's been a long time coming it's about two years various delays due to um oh however reported political developments and then covet have really um pushed this this project back quite a lot so we've been waiting a very very long time so i'm delighted that this day has finally arrived so in this nicely refurbished new lab we're going to have the new stm fm system in this space as you can see it's empty right now um up here is a camera that's going to capture the various stages of construction of this system it's an ultra high vacuum system it's a very it's a low temperature system as well so there's lots of stainless steel bits to assemble like a massive big lego puzzle and um that's what's going to occupy us for the next few days [Laughter] chap's just um tying the the lorry closer into the wall we're obviously going to unload from the side doors of the vehicle here and then we're going to use the forklift to transport the crates just up the hill there and then we struggle with pallet trucks to get it into the building [Music] exactly yeah yeah exactly sort of just in the early stages of bringing stuff in these particular boxes are the controller that really is at the heart of it um in terms of controlling the stm so oh it's started raining of course it has how many of these systems have you installed of unicircle systems in general in in europe um okay well this is the first in the uk that's true so all the crates are off the lorry um they're being undrilled all the bolts are being taken out at the moment i will get a drill in my hand and start helping out i promise we're just trying to sort of drill bit at the moment so you can take one out oh the other one should be left in until we can see just one one of each of these okay perfect okay but any on the top you can take out [Music] you know where you are when you've got a power drill in your hand [Music] we planned it [Music] [Music] [Music] [Music] [Music] [Laughter] [Music] so it's day two of the installation and a huge amount has changed already so all this wooden platform that was there we're gonna have to rebuild that platform because at the moment it's slightly dangerous this magnet has been dropped in that magnet is about the same height as i am will be filled with liquid helium but 90 liters of hit liquid helium in there the um uhv the ultra high vacuum chambers have been added on top everything's been trained in it's been um really really fun to watch this all emerge and to see it here now after sort of waiting for two years for this to happen is great is is just just wonderful the other great thing about it is the um guy who's really worth standing back and watching them do all this stuff because like a magician like a master magician in terms of assembling this guy called thomas berghaus thomas did his phd right at the start at the birth at the origin of stm and the group he was in was one of the groups that was quickest to follow on from the ibm invention of the the scanning tunneling microscope and pick up and get that technology and start build their own stm the hard stuff in the beginning normally goes pretty quick and then there will be days where uh the tiny things are going to be happening so like assembling the stm to the cryostat and the wiring and everything and then you do one wire per hour or something and nobody will see what you're doing really great to talk with thomas because he was responsible for designing the stm1 the omicron stm1 that i use for my phd we will assemble a lot of components like the titanium supplement like the lead optics the sputter iron gun then we will assemble the transfer manipulators and when we then have all flanges closed with some function and so then we will pump it down and leak check and uh next step will be then go for uh 3 with the bake out and everything and yeah before do some tests with the sdms and eventually then after the bake out cool the thing down and yeah then the great overcomes [Music] okay so it's chamber and we can go on the other side of this chamber um which is going to have to be lifted in over the top oh it's high enough it's not quite high enough to clear it [Music] thank you [Music] okay thank you sean touchdown okay thank you so yeah we've just trained in this chamber which um ultimately is going to have this thing on top of it going all the way down um directly above the magnet um and we're going to see all that come together over the course of the next few i'd like to say days but it's going to be weeks really probably a month before we're going to see atoms so we are going just down to see the um the microscope now we're at day 13. thomas has now left to go back to germany thomas and uh japanese engineers so the company that supplies the instrument is a company called unisoco uh will be back in 15th of november when we'll start the the system will be at a good vacuum at that stage okay so you can feel it's really hot in here oh wow um and the reason it's really hot in here is because well things have first of all things have changed a lot haven't they since the last time you were here tables in place magnets down there this long transfer tube's in place the whole thing is covered with tin foil because we're heating it up and the reason we're heating it up is because ultimately i'll take that off ultimately um we want to get to what's called an ultra high vacuum in here i've talked about this in other 60 symbols videos at length but what we're doing is we're heating up the system and the tin foil is there just to keep everything nice and toasty um the key contaminant if we don't do this is water the internal surface is all covered with a very thin film of water and if we don't heat and pump that water just stays there for months if not years and just leaks off the walls gradually and pollutes our vacuum what we're doing now is we're boiling off the water basically accelerating the process pumping it all away so when everything cools down after about a week um we'll get a much better vacuum and then our pressure will be oh about a million million times um lower than atmospheric pressure comparable to the pressure you get on the moon and on a good day maybe even comparable to the pressures you get in some regions of deep space so it's a pretty low pressure and we need those vacuums because we want to work with atomically clean samples if we want contaminants there or if we want molecules on the surface that aren't part of this you know the original material uh that's because we want to introduce them we don't want you know oxygen just and other contaminants from the air co etc and indeed water landing on our sample and polluting it so this is why we we work this hard to get the vacuum where does the water go the water gets pumped away by the pumps so basically by turbo pumps uh so by um there are pumps down here which are basically coming along here it's coming along these tubes and then out the exhaust of this this pump down here so it just gets all pumped away that's a very happy wheel did they provide the foil they even provided the foil wonderful absolutely wonderful so our day 45 been up for day for 45 days in a row with this that's not really it reached to its base temperature which is about 300 milli kelvin which is about 10 times colder than out in the deepest darkest depths of the universe because the cosmic microwave background radiation is around 2.7 k we have yutaka visiting us from the company unisocker who's the ceo of the of unisoco who um has played an absolute storm or has been incredibly good and another magician like thomas in terms of getting the system up and running training us on how to use it to get down to those type of temperatures we first of all liquid nitrogen and liquid helium lots and lots of liquid helium that goes into that massive magnet and the stm is down here right at the bottom all the way down here or close to the bottom the stm this is a very i think you saw this before when it was out this insert that goes down there to get down to 300 milli kelvin um we use something called helium 3 a bottle of which let me see there we go this is now pretty much empty not entirely empty but pretty much empty because it's in there at the moment actually it's going in the system that's about 30 000 pounds so as thomas said you pay for helium-3 which is an isotope of helium by the atom it's extremely expensive but barring any disaster which we can never rule out we basically um the the helium 3 can be effectively recycled it's absorbed and then turns into the gas phase and is reabsorbed and condensed and then goes back into the gas phase etc so but it's an expensive business and liquid helium helium 4 is also not particularly inexpensive either and it's actually a dwindling resource so we are i am very conscious of um uh all these various issues let's put it that way we are at i believe day 65 um and we've been left on our own the training wheels are off the attacker worked extremely hard for four weeks or so um really doing all the commissioning and all the site acceptance in terms of what are the noise levels does the magnet work when we go up to the highest fields does everything cool and yes everything cools and down to 320 milli kelvin which as i might have mentioned before is 10 times colder than the cosmic microwave background radiation in the universe so the leftover remnants of the big bang radiation um uh so that's that's that's a pretty cold place down in that magnet um can be a pretty cold place in the universe not only does it get down to that temperature it gets down to that temperature and stays there for 63 hours what we see is our hold time is 63 hours that's that's very helpful for us it allows us to do prolonged experiments what we'd really like to do is to take the tip which is coated with gold atoms because we've deliberately crushed into the surface and then go dutch and drop down an atom and dutch and drop down another atom and die and if we could do that that would be a little short and magical it would be really neat however what happens is that yes on occasion and let me change the contrast here we can indeed put down single atoms these little features but also the problem is sometimes when we do exactly the same process larger clusters appear so we we we have some degree of control but not a great degree of control over just how many gold atoms we put down but the good thing is that there's a reasonably high probability of putting down single gold atoms and then what we want to do is then try and shunt those across the surface so these lines in the background well imagine taking a crystal in this case it's gold but it could be pretty much any crystal and you slice that open to expose a surface now the atoms that are at that surface are much less happy than they were when they're in the bulk because when they were in the bulk they interacted with their neighbors they have a certain valence they want that valence they have a certain number of bonds they want to form but when you hack through the the um the crystal to expose that surface not always hacking through sometimes it's a little bit more nuanced and careful than that but when you expose that surface those atoms at the surface are in a different state than the atoms in the bulk and they're much more reactive their energy is higher so what they will do um is move around as much as possible usually given the constraints of how much thermal energy there is but they will move around to try and minimize their energy to try to somehow drop back down into a situation that gets them closer to where they were in the bulk in terms of the overall energy and that's a process called surface reconstruction and it's absolutely fascinating because so many different surfaces form a range of different reconstructions here's here's an example of one really pretty one which is very famous that's just one example there are literally thousands tens of thousands or hundreds of thousands of different patterns out there that the atoms can find and this is one of them this is another famous one this is called the herringbone reconstruction of gold what you have here is these larger or these brighter regions there's effectively a rumpling in the surface so that some atoms move up some atoms move down it's a very very small rumpling and again they're doing that to try to relieve the strain to try to bring their energy back down and this reconstruction is very famous in terms of uh it's a very stringent test of the the stability of a microscope and the resolving power of the microscope in terms of can you resolve that herringbone can you um see that without a great deal of noise so the tip's moving back and forth and it's measuring uh we're telling it to keep the current between the tip and the sample constant and to keep that current constant what it has to do is move back and forth and follow the topography of the surface because it's a feedback loop and it's comparing the current value it's comparing the value of the current it's measuring against the value of the current you want which we call the setpoint current that feedback loop has a certain response time so if you drive past the point at which the feedback loop can respond it can at worst case crash so yeah this is the tunnel current that it's measuring and this is the motion of the zed how do we get such fine control over the position of the tip because we need to move to be able to measure not down to the atomic limit but actually that precision better than the diameter of the atom of an atom so we use piezoelectric elements those sound like rather esoteric technology but they're not you know those barbecue lighter things that you go click click and it gives you a spark at the end and you light your barbecue what those are is in the handle of those is a piezoelectric crystal and in that case what happens the property of the piezoelectric crystals is when you distort them when you strain them you build a big voltage up across them it can actually be kilovolts many kilovolts that's voltage is large enough to break down air so you get the little spark um turn that idea in its head and perhaps use piezos that are a little bit higher quality than those you get in barbecue lighters and if you apply a voltage to the piezoelectric crystal it will distort and you can if you've got good high voltage amplifiers no low noise high voltage amplifiers and good crystals then you can control the position of the tip down to the picometer level that's a hundredth of the diameter of an atom you can see here these air legs are in place to try to decouple or to decouple the instrument from this the surrounding building because we're trying to work down at a level as i've just said of fractions of an atomic diameter the floor in which you're standing shown and which well i'm sort of sitting um is oscillating up and down vibrating on the down at the level of microns so about a million times bigger in terms of the the the amplitude of those oscillations than the type of precision we want to get to so we need to decouple the system from the the external building and one key way of doing that is with these pneumatic legs which lift the entire system up so it's supported by those legs so these are the same this is where the samples are introduced this is called a load lock we'd um open this up we'd unscrew this we put our sample in on the end of this arm then we pump this down then we'd open that valve then we'd move our sample into this chamber and then we bring this one in to couple with that pick it up take this arm back shut this off so now it's back it's not it's isolated from this load lock and we can then wait for the pressure to recover and then we can take our sample and bring it all the way in here to this monstrous beast of a transfer arm all the way up there and then to transfer samples into the microscope they're at the end of this arm and then we're going to go all the way down to the bottom of the magnet well close to the not quite the bottom of the magnet but close to the bottom of the magnet we're looking at individual atoms those atoms are fairly weakly bound because you can see even here the atom that it's like it's got discontinuities in it it's got wobbliness in it because the tip is interacting um with the atom and sort of dragging it and shifting its position a little bit interesting question is what color is an atom so important thing to realize with scanning for a microscope is a microscope like no other we have that tip and our image is based on the current that's flowing between the tip and the sample and it's a quantum mechanical tunneling current um this is quantum mechanics in action you're seeing here but the microscope itself has no optics no lenses no mirrors it's it's not imaging in the sense that a traditional microscope images and our image is based on the amount of current we measure at different parts in the image that's that's basically what it is so we can define whatever color scheme we like so at the moment our atoms are sort of ready yellow if you want them sort of a bit blue there they go if you perhaps prefer to have them a bit sort of coppery like that or maybe um even a sort of slightly different goalie does that look gold to you looks more green to me let's see what winter's like oh winter's like that and philippe's developed to put together his own palette which is called the good one which looks um red and yellow again you see these sharp changes see this chart where it looks like the the atom has been sliced that's because it's interacting with the tip um these other shadowy features are probably almost certainly you see each one's got a tiny little ghost image you get used to seeing these things sometimes it's difficult to spot them but this tiny little ghost very faint ghost is probably because we've got a slight double on our tip so of course as soon as you left started to work incredibly well almost as soon as you went out the door so let me turn the screen view around the camera view ran so you can see what's going on so i've spent a few happy hours depositing atoms from the tip these all these features that are roughly the same size are individual almost certainly gold atoms that come off the tip but we've crushed the tip quite heavily into the gold sample so the tip is covered with gold atoms we've got a reasonably high probability when we touch the tip into the sample of depositing a single gold atom actually i believe this one which is slightly bigger than the rest the eagle eyed among you might be able to spot i believe this might be a dime or maybe two gold atoms but we also have a probability for putting down rather more than one gold atom and that's what these little clusters are these brighter features so it is now where's the bloody camera down there isn't it so it is now 20 plus three in the morning and it's been going pretty well i'm a bit knackered but my this is fun i'm building a structure atom by atom let me flip the camera around so you can see what i'm doing so this is a little rectangle of atoms each gold atom pushed in place um before and after hopefully will appear on the screen each blob there each circle is a single gold atom and what i'm hoping is that we can find some electrons within there within that little container it probably needs to be compacted a little bit more and the atoms move together a little bit more but it's getting there it's it's getting there you could ask a very very valid question ask is could you automate this yes it could be automating a number of groups um have automated the manipulation of atoms using scanning probes and yes it's definitely something that's on the agenda for us indeed we've we've made moves in that direction before um there is something to be said though with a brand new instrument like this one to sort of get your hands dirty doing the manipulation um sort of by hand as it were and um getting a feel for how the instrument behaves how the feed like feedback loop behaves etc um though i must admit it getting to half three in the morning um perhaps it really should be a question of handing it over to the computer because the computer doesn't get tired quite like we do so spend some time trying to build structures atom by atom to contain electrons and then realize well nature can do the job even better and i don't have to spend a lot of time putting things together moving atoms across the surface so this particular gold surface we found these beautiful triangular structure that is or you can see the scale bar at the bottom 10 nanometers so it's about 10 nanometers edge and it's pretty much a perfect equilateral triangle that's fun enough but over here what we can see and it's overwriting the previous image but what you can see is the electron waves that are trapped within that structure it's absolutely stunning it's so much fun just changing the energy and watching how these waves these wave patterns change i am blown away by the stability and just capability this instrument it is fantastic out of the can and you can glue a tip onto it or blue tech oh you can yeah you can perhaps not in in the real case we don't blue tack it on we actually do glue it on but actually the gluing is probably just about that accurate [Music]

Channel: Sixty Symbols

Views: 231,296

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Id: YI9Zz2HRlhQ

Length: 27min 54sec (1674 seconds)

Published: Tue Jan 11 2022