Introduction: From Diamond Light Source, this is the Diamond podcast.
Meera Senthilingam: Hello, and welcome to the Diamond Light Source podcast where we take a look at the latest science from the UK’s national synchrotron facility. In this edition of the podcast we’re peering into the miniscule world of nanoscience, to find out how something as big as Diamond can look into the world of science on a scale as small as the nanoscale. We’ll be hearing the latest news from Diamond, including the opening of two new beamlines, and delving into the nanoworld, we’ll be hearing about a new way to read and store data that could revolutionise computers, sound systems and pretty much anything else that requires a hard drive.
Chris Marrows: The problem with hard disks is that they contain moving parts, so if you’re not going to have any moving parts then the only thing you’re allowed to move is the information itself. If you can visualise this magnetic structure, you can turn on the current and you would see all these little regions travelling along, kind of like a train blown along by this wind of electrons.
Meera: And moving from computers to chemical reactions, we’ll be finding out how the by product of a particular species of bacteria could help industry become a lot greener.
Vicky Coker: Currently in industry, if you make magnetite or cobalt ferrite, I believe you make it at very high temperatures, whereas the bacteria are providing the energy to the system, so we think this is a more environmentally friendly route and they might actually make the nanoparticles better than industry as well.
Meera: But just how do these bacteria actually produce the particles that we want? I’m Meera Senthilingam, and this is the Diamond Light Source podcast.
Voice-over: This is the Diamond podcast. For more information look us up online at www.diamond.ac.uk/podcast.
Meera: Before we delve into the tiny world of Nanoscience, let’s join Sarah Bucknall from Diamond’s Communications team to find out what Diamond has been up to in recent months. So first Sarah, two new beamlines have come into operation…
Sarah Bucknall: So recently we have had first light on two of our Phase II beamlines, that means it’s the first time we got synchrotron light into the optics hutches on two beamlines. They were I07, the Surface and Interface Diffraction Beamline, and I12, the Joint Engineering, Environment and Processing Beamline.
Sarah: I07 will use high resolution X-rays to investigate the structure of surfaces and interfaces under different environmental conditions and I12 is a multi-purpose beamline used by practitioners in the engineering, materials sciences, imaging, processing and earth sciences. It’s really exciting when we get the beam of synchrotron light to the beamline for the first time because it confirms that what we’ve built is working, and it means that we’re not far off from welcoming the first users, and we’re hoping to get them to I07 and I12 by the end of 2009.
Sarah: Well it was Tuesday 12 May, and it’s the first time that two beamlines have achieved first light on the same day. But that’s not surprising really because it’s a really busy year for Diamond – we’ve got five experimental stations coming online this year, and that will bring the total of operational beamlines to 18, and this keeps up right on track to complete Phase II by 2012, and at that point we’ll have 22 beamlines in operation.
Meera: OK, so five more beamlines are being developed, and the first one opened two and a half years ago, so good science has been going on here for a while now and papers are being published as a result…
Sarah: That’s right, as you say our Phase I beamlines have been operational now since January 2007, so we’re starting to get some high impact publications and we’ve had some recent publications in Science and Physical Review B, featuring research from our Extreme Conditions beamline I15, that’s the Science paper and that was on how earthquake waves travel through the Earth, and then the Physical Review B paper was from our Nanoscience beamline, and there’ll be more on that later from Chris Marrows.
Meera: So as well as the science you’ve also had a few interesting visits recently?
Sarah: Yes, we had another Royal visit back in April, we had a visit from the Duke of York, Prince Andrew and whilst he was here he met the finalists of the National Science Competition, this was a contest for 13 – 19 year olds to become the young scientist or young technologist of the year.
Sarah: Yes, well part of the finalist’s prize was a visit to Diamond so we organised for their visit to take place on the same day as Prince Andrew’s, and they thoroughly enjoyed the opportunity to see the facility and to meet our scientists and engineers and it was definitely a bonus to get to meet the Duke of York as well. We really enjoyed welcoming the finalists and it was great to encourage them into careers in science and engineering.
Meera: Well you also had your Inside Diamond day recently, so how did that go?
Sarah: Yes, that went really well. It was on Saturday 23rd May and over 200 people came. This time we targeted people who are into the arts by featuring the events as part of Artweeks, which is a festival of visual arts events running throughout Oxfordshire. It was really nice to welcome the Artweeks audience and talk to them about science, so that went really well. The next Inside Diamond is on Saturday 3rd October and once again you’ll be able to register via our website.
Meera: Now the science at Diamond isn’t possible without your users, so you’re now actually setting up a committee to help your users here?
Sarah: That’s right, Diamond is really keen to listen to its users and provide them with a platform for dialogue so we can work with them to get the best out of the facility. So the Diamond User Committee launches on the 23rd of June, this is an opportunity for the users to tell us what it is that they want from Diamond. If anybody is interested in finding out any more about this then they can email email@example.com.
Meera: So as well as this are there other events taking place over the summer?
Sarah: Yes, there’s going to be lots of specialist science workshops at Diamond throughout the summer and then in September we’ve got a major international conference on small angle scattering and more information on all of these can be found on our website.
Meera: And now something exciting coming up this summer as well is the World Conference of Science Journalists, so how is Diamond getting involved with that?
Sarah: Diamond is involved in a number of ways, we’re taking part in the official welcome reception which is at the conference venue on Tuesday 30th June and there will also be a press briefing on the Thursday and that’s at the French Embassy with some of our fellow European light sources, and then after the conference we’ll be hosting some visits on the Friday along with some other Oxfordshire facilities, JET, ISIS and the Central Laser Facility, and as well as all this there will be an international meeting of light source communicators on the Friday. It’s going to be a really busy week because as well as the world conference at the same time we’ve got one of our science and art projects, Designs for Life, at the Royal Society Summer Exhibition, so there’s lots going on to keep us all busy!
Meera: Thanks Sarah. Diamond’s Sarah Bucknall, who’ll be back with more of the latest news from Diamond in the next podcast.
Meera: Now this month we’re finding out about how Diamond is helping scientists investigate the nanoworld. So now we hear from Sarnjeet Dhesi, Principal Beamline Scientist on Diamond’s Nanoscience beamline to find out a bit more about just what Nanoscience is.
Sarnjeet Dhesi: Well I guess nanoscience is about understanding and manipulating materials at the atomic level. Well in a nutshell I think materials are profoundly affected by quantum mechanics as you scale them down to the nanoscale, and this means that a material that is an insulator normally can become a conductor down at the nanoscale, or a material that is opaque in the macroscopic world can become transparent, so it’s all about engineering materials so that they have different properties when they are scaled down to the nanoscale.
Sarnjeet: Well the nanoscale is down at the atomic level, the nano part of the word means a billionth of a metre, so a billionth of a metre is round about 10 atoms wide, so it really is down at the atomic scale of matter.
Meera: And why is it important to understand things on this level? I mean what kind of things can you learn?
Sarnjeet: Well in my particular case I try to understand magnetism and magnetism is very important for hard disks. The reason why we’ve got from a room that contains a few sheets of paper of information to ipods and hard disks that store thousands of songs and movie clips is because the magnetic particles that store the information in the hard disks have got smaller and smaller and nowadays they’re only a few nm wide and it’s by understanding how these magnetic materials behave down at the nanoscale that we can improve magnetic disks for instance. But that’s my particular area – there are all kinds of areas where materials are used down at the nanoscale. Sunscreen for instance, paints and pigments all contain nanoparticles that give them the properties that they have.
Meera: So why does something as big as the Diamond used to look at things on this small scale? How does synchrotron light focus down to look at these?
Sarnjeet: Well Diamond produces very intense rays of X-rays, and we use these X-rays to study materials down at the nanoscale. So for instance on my instrument we use the X-rays to illuminate the sample and this ejects electrons from the sample and those electrons are then used as an electron microscope to image the material and find out the properties of the material.
Meera: So we’re actually located down by your beamline now, so which beamline is this and what is this large machine in front of us that is almost the same size as a tractor and yet it’s looking at things on the nanoscale?
Sarnjeet: Well this is the nanoscience beamline and this is called a Photo Emission Electron Microscope, also known as a PEEM. So the electrons are ejected from the sample by the X-rays and then we use a series of electron lenses that we can see over here and we use these to focus ad project the electrons onto a detector where we form a very detailed image of the surface, and by doing this we can find out lots of interesting things about materials and the really nice thing about X-rays is that we can choose the X-ray energy to be sensitive to particular elements within a sample. So if we’ve got a sample made up of lots of different elements we can study each element of the material…
Sarnjeet: At the same time, yes. And through this we can understand if one part of the material is behaving in the right way or the wrong way, and we can see what we might need to do to the material to improve it.
Meera: So do the X-rays just come straight out of the synchrotron and into this electron microscope? I mean what happens in between?
Meera: What kind of experiments are taking place here, and what are the potential applications of these?
Sarnjeet: Well on this beamline we concentrate quite a lot on magnetism, so we study a branch of physics called spintronics. We all know about electronics, where we exploit the charge of the electron, but in the past couple of decades there’s been a new emerging technology called spintronics where we also exploit the spin of the electron, and this beamline is very good at understanding the fundamental aspects of the spin of an electron in a material. For instance we might use the chemical specific nature of the X-rays to study two sides of an interface of two magnetic materials so we tune the X-ray energy to study one part of the interface and understand the magnetism on that side and then we tune the energy of the X-rays to another part of the material to understand the magnetic material on the other side of the interface. So we really try to understand something about the magnetic glue that bonds these two materials together, and that’s really crucially important in terms of hard disks and the sensors that are used inside them to detect the tiny magnetism that is coming off the nanoparticles that are used in hard disks these days.
Meera: But it seems like quite a versatile machine so can other things as well as spintronics be looked into?
Sarnjeet: Yes, it’s very versatile, and there’s quite a wide community of researchers that are always coming up with new and novel materials that are just ideal to be studied here at Diamond with this instrument, and because we’ve got a synchrotron source over here and it’s not a continuous source, it’s a pulsed source, it’s almost like a laser source, we can use the pulsed nature of the X-rays to do timing experiments so we can study materials and what happens to them down to a millionth of a millionth of a second. And continuing the theme of spintronics we can look at magnetic domains and see how an electrical current can move those domains, how those magnetic domains can be manipulated by electrical currents. So as you can see there’s a lot going on here at Diamond and I think the future is very bright.
Meera: Diamond’s Principal Nanoscience Beamline Scientist Sarnjeet Dhesi explaining how the electron microscope at Diamond can help us understand more about magnetism on the nanoscale.
Voiceover: Did you know that Diamond’s floor area is 45, 000 m2? That’s almost the same as 8 St Paul’s Cathedrals.
Meera: We’ve had an overview of the role synchrotrons can play in nanoscience research, but now we peer a little bit closer to see how something as small as a nanowire could be used to transfer data faster than the current computer hard drives we see today. Chris Marrows is working in this new field of information transfer and storage at the University of Leeds, and he explained how he is developing this technology. But to put it into perspective, he began be explaining how our current hard drives actually work.
Chris Marrows: So a hard drive, what it looks like if you open the box is a little bit like an old fashioned record player. So you have a spinning disk that contains all the information in lots of tracks, little circular tracks one inside the other inside the other, so rather than one big spiral like a record there’s lots of these circular tracks. And then there’s a little head, we call it, that reads and writes the information, sitting on the end of an arm like a record player arm, and then the information that’s recorded on the track will whizz pass the head as the disk spins around, and essentially what the disk is, is just billions and billions of tiny little magnets. And each one of them can be magnetised one way or the other, if it’s pointing one way or the other you can use that to record a digital zero or a digital one so the little head can create a magnetic field and flip one of those things around, to point in a certain direction to record a bit of information and then there’s a little tiny sensor that can read that back again when you want to read back the file to play your music track or look at your photo or access your bank statement, whatever it is that that information represents.
Meera: So this current method of memory has information stored in one place and a reader that will basically interact with it in order to try and read the information. But you’re working on a new way in which information can be read and stored?
Chris: Yes that’s right. The problem with hard disks is that they contain moving parts. This disk is spinning round at thousands of revolutions a minute – imagine keeping this head, it doesn’t touch the disk it has to fly just above it at a distance of only a few nanometres. The analogy that is used is keeping that head just above the disk is like flying a jet fighter an inch above the ground, it takes a phenomenal amount of engineering to do that. So somehow that works most of the time, but disk drives do fail, they are the bits that most of the time do fail in computers because they contain moving parts and this is why we have to worry about backing up information and having multiple copies.
Meera: So the way that you are trying to improve this then is rather than having the information stored in a particular place you are going to try and make it so that information basically moves around a hard drive?
Chris: Yeah, so you have to make something if, where you’re not going to have any moving parts then the only thing you’re allowed to move is the information itself within the structure. So there’s some new physics that’s been discovered in the last few years that lets you do that.
Meera: And so how is your research looking into creating this movement of information?
Chris: Maybe the best way to explain that is to think about what the information looks like. So we make what we call a magnetic nanowire, so this is a wire of magnetic materials and it may be only ten or a hundred nanometres across and then you magnetise little regions of it, north or south say, and you magnetise those little bits. And as a physicists you would call those regions domains, and then the joins between those things we call domain walls. So you can think of the domains as little rooms full of magnetism pointing in a certain direction and the wall is the join between them. But there’s nothing physical there, it’s purely just a magnetic structure. And then it turns out you can move that whole thing along, you flow an electric current down the wire.
Meera: So what do you mean move the whole thing along, do you move the walls essentially?
Chris: Yeah, all the walls would move along. If you could visualise this magnetic structure, which is what we actually use the microscope at Diamond to do, then you would turn on the current and you would see all these little regions travelling along. Kind of like a little train, they should all move along together, they should be sort of blown along at the same rate by this wind of electrons that’s flowing through them, so the wire sits still but the data moves along it, and then if you’re sitting by the wire with some sort of sensor then you would see these things pass you and you would get back your stream of data which you would then convert into music or video or whatever it would be.
Meera: So by injecting an electronic current into this nanowire you are essentially just pushing these walls along the nanowire and therefore moving the information along this wire?
Chris: Absolutely yes, that’s exactly what happens. So there is nothing physically moving except the data itself.
Meera: And so therefore where would this data be taken in order for it to be read, and therefore used?
Chris: Well, what you would have is like a reader, something very like the head in a hard disk, you would have some little magnetic sensor just sitting by the side of the track and it would feel the magnetic fields from each bit as they passed, and that would be converted back to an electrical signal and that would be used by the computer or mobile phone or whatever it is.
Meera: So what are you currently looking into in order to develop this technology further?
Chris: We know that this physics works, but the problem that we have at the moment is that we need very very high densities of current, almost at the point where we will start to have these wires destroy themselves, either by melting or just physically ripped apart by the force of so many electrons moving through them. We’ve got to make this work with much much smaller currents. So by understanding the details of how the current and the magnetism interact with each other we have a few schemes where we think we will be able to reduce this by maybe tenfold or a hundredfold.
Meera: And so what aspect of this research are you using synchrotron light to help you look at and understand?
Chris: So we’ve done some experiments at the nanoscience beamline at Diamond and really it’s a microscope, and it’s a microscope that lets you see magnetism. So we make our wires and we connect them up to some electrical contacts, and these things are prepared on the surface of a chip, a chip of silicon or something like that, just in the way they would be used, and we take these chips down to Diamond, we put them in the microscope and we shine synchrotron X-rays on there and we’re able to visualise the magnetism in the wire. So we’re seeing this structure, the domains and the domain walls which represent the data, and then seeing the way it reacts when you stimulate it when you apply currents, so we can apply currents and then just directly see what happens.
Meera: And where would you say you are currently with this, what do you think we have understood so far and when do you think it will be available to use this as a form of memory?
Chris: We’re trying to change the magnetic properties of the material itself by doping, so this means putting in small amounts of impurities and they are things that the electrons can interact with, and we think if we find the right impurities there will be a very strong interaction, and this will mean you don’t need so many electrons to get the same effect. We think within a year or two we will have found the right impurities that will give us a big improvement in terms of the level of current that we need. Then turning that into a technology that’s for sale will probably take several more years.
Meera: That was Chris Marrows from the University of Leeds explaining why he’s using nanowires to develop faster, cheaper and greater information storage. Now as well as computer technology the nanoscience beamline can help us understand the reactions and products of bacteria. Vicky Coker is from the University of Manchester and she’s been looking at a certain species of bacteria that produce magnetic nanoparticles that are not only crucial catalysts in industrial processes but can also be pioneered for cancer therapy and drug delivery. She explained how she is looking into this.
Vicky Coker: I am currently looking into how iron (III) reducing bacteria can produce magnetic nanoparticles such as magnetite and how these could be used in industrial processes.
Vicky: They will do it at room temperature rather than at high temperature, which is what currently happens in industrial processes. Magnetite is used in many different industries for many different applications like uses in data storage in magnetic recording media and also in medical applications such as drug delivery.
Vicky: These bacteria are ubiquitous in the environment and they are found below the surface in an anoxic zone where oxygen is no longer available. Instead of breathing oxygen like me or you they breathe and respire on oxidised minerals such as Iron (III) or Manganese (IV) and they reduce these minerals by transferring electrons from organic matter to the Iron (III) mineral and in doing so they conserve energy for life, and as a byproduct of this they produce reduced minerals such as magnetite and they just happen to be in a nano form. So they are not doing it deliberately or for any gain to themselves except to respire.
Meera: So what are these bacteria called?
Vicky: They are Iron (III) reducing bacteria. The bacterium is called Geobacter sulfurreducens.
Meera: You say they are ubiquitous but whereabouts are they found?
Vicky: You can find them at acid mine drainage sites, or where-ever you find a high level of iron or manganese together with a high organic content so they have basically the electrons to transfer and also the iron mineral to act as the electron acceptor.
Meera: And how have you been using synchrotron light and so the nanoscience beamline at Diamond to help your research and to help you look into this?
Vicky: OK, because the nanoparticles are very small there are only a couple of techniques we can use to analyse them, we can’t just look at them in order to analyse what we’ve made. We use X-ray Magnetic Circular Dichroism (XMCD) at the nanoscience beamline in order to determine the actual structure of the magnetite that we have formed. Magnetite is Fe3O4, it has one iron (II) cation for every two iron (III) cations so it’s a mixed valence iron oxide and XMCD, the technique that we use at the nanoscience beamline which is one of the only techniques that can determine how much of each of those three different iron cations we have present in our magnetite.
Meera: How is it capable of doing that, what is the technique?
Vicky: It’s an X-ray absorption technique, it’s element specific, so you target the correct energy range for, say, iron, and then you use it to collect X-ray absorption spectra within a magnetic field parallel and anti-parallel to the beam direction and the difference between these two X-ray absorption spectra is the X-ray Magnetic Circular Dichroism spectra, and this reflects the structure of the material that you’ve probed with your X-ray beam.
Meera: So how does understanding the magnetism of these particles and of these bacteria help you understand more about how magnetite is made and how the bacteria are working?
Vicky: OK, because the bacteria are growing, and they only grow magnetite within anoxic environments we’ve discovered that the amount of iron (II) within the magnetite is often larger than you would find in a normal magnetite sample that had just been left out in air, because they are growing without oxygen and this is important because in certain different industrial applications magnetite can be used as a remover of environmental contaminants, and it is the iron (II) within the magnetite that achieves this. So if you have a bit more iron (II) there than you would normally have then the magnetite is even better at its job than it would be normally. That coupled with the fact that it’s a nanoparticle so you have a high surface area leads to a really good product to reduce environmental contaminants such as chromium.
Meera: Now you know that these bacteria are capable of doing this, how could it be scaled up and used for industrial purposes?
Vicky: Now that we know that they can do it we’ve been trying to sort of apply different techniques in order to make it in large quantities and that’s really the next step, we haven’t done that yet. But you would use a big bio-reactor to grow up lots of bacteria, seed it with lots of iron (III) oxides and hopefully get out loads of magnetite that could then be used.
Meera: So would the main uses of this magnetite that’s made then be for reducing environmental contamination?
Vicky: We’ve also been investigating how, if you use a different transition metal other than iron, such as cobalt or nickel into the structure of the magnetite you can alter the magnetic properties and that can lead to it having different uses and applications. We’ve been using the XMCD because it’s element and site specific, in order to probe the magnetite that we make that contains the cobalt and the nickel, which makes it a ferrite rather than a magnetite to see how much cobalt or nickel or manganese that we have got within the structure, and then we’ve done some other techniques that show that the material has altered in magnetic properties.
Meera: Are the bacteria incorporating these other transition metals into the magnetite then to make these ferrites?
Vicky: They are. We weren’t sure that they would be able to do it because it’s not something that they come across in the environment, like high amounts of iron and cobalt together, but when you feed them with an iron (III) oxide that contains cobalt co-precipitated within the structure they will take the iron and the cobalt together and reform it into a cobalt ferrite nanoparticle.
Meera: Now why would using these bacteria to make magnetite and these metal oxides be better than the current way industry makes them?
Vicky: Currently in industry if you make magnetite and cobalt ferrite I believe you make it at very high temperatures, whereas the bacteria, we’re using them as our energy source and so they are providing the energy to the system to change the structure of the mineral into this magnetic nanoparticle, so we think this is a more environmentally friendly route, and they might actually make the nanoparticles better than industry as well.
Meera: What are the applications of this magnetite then and the metalloids that can be made?
Vicky: There are various different applications in industry for magnetic nanoparticles such as data storage in magnetic recording media, ferro-fluids for use in heat transfer and they can also be used as catalysts. A more novel application is in different medical uses such as in drug delivery and in different imaging techniques but these are still being investigated and I don’t think they are actually being used for this currently and it’s under research.
Meera: Vicky Coker from the University of Manchester explaining how iron (III) reducing bacteria can produce nanoparticles that are not only crucial to industry but are made using a more economical and environmentally friendly method. Now that’s it for this edition of the Diamond podcast but do join us again in August when we’ll be finding out how synchrotron light can be used to investigate our cultural heritage. In the meantime if you have any questions about Diamond or the research that is taking place there, the email address is firstname.lastname@example.org. Thank you to Sarah Bucknall, Sarnjeet Dhesi, Chris Marrows and Vicky Coker. I’m Meera Senthilingam, thank you for listening and see you next time.
Voiceover: The Diamond podcast is brought to you by Diamond Light Source and produced by the Naked Scientists.com. There’s more information on our website at www.diamond.ac.uk/podcast.
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