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Need to investigate nanostructures? — This way, please. There’s no waiting line here!

АНИ «ФИАН-информ» недавно опубликовал интервью зав. лабораторией «Рентгеновских методов диагностики наноструктур» А.Г. Турьянского пресс-секретарю РАН С.А. Шаракшанэ, которое вызвало большой интерес. Публикуем английский перевод статьи                 

 

Interview with A.G. Turiyanskiy, Doctor of Mathematics and Physics, Head of the X-ray Nanostructure Diagnostics Laboratory at the Lebedev Physical Institute of the Russian Academy of Sciences

 

    A physicist should not have any qualms about speaking a language that is not accessible to laymen. Whose fault is it if it is inaccessible? Alas, it is us who are at fault: we failed to study — either in school or in university — many of the things that have become important to humanity. So let us make mutual effort: let the reader try to grasp new, unheard of stuff, and let the scientist try to tell his story in the most popular way possible.

    To start with, let us talk about X-ray radiation and synchrotrons. Our purpose is not to revise a section of a physics textbook, but to grasp a stunning picture: in the very forefront of science, a major roadblock has emerged affecting various areas of high-tech research. Grasp the picture and appreciate the ingenuity of the solution proposed by a Swedish-Russian team of physicists. So, to sum up: we are going to talk of a roadblock and a way to bypass it.

    Some introduction is still necessary to get an idea of what X-ray radiation and synchrotrons are about and what they are in aid of.

    There is this notion: nanolevel. Nanometer is a unit of length so small that it is close to the size of a simple molecule (one millionth of a millimeter). The microworld became an object of successful physical study over a century ago. Now, after a hundred years, science has advanced so greatly that this area is turning into a ground for engineering activity. It is where we know what we want to achieve — we set an objective and get a result — and this is how man obtains new materials and new technology today. In spite of their knowledge gaps, the readers will have to wrap their head around this stuff as it is exactly those materials and technologies that will define tomorrow’s civilization, both in terms of industry and in terms of people’s everyday life.

    Today, nanostructures are ubiquitous: they are at work in our cell phone, tablet or notebook which we always wish to have a larger memory and to operate faster and faster. That is why nanolevel research of unprecedented activity is carried on by the world’s laboratories. Apart from physicists, engaged are metallurgists, chemists, biologists, communication experts, and so on. In this way, new drugs and new composite materials are born — thousands of new compounds are synthesized every year!

    Now, the key point which may seem vague to many readers, is that today, the X-ray analysis is becoming the main source of new findings for researchers of various specializations. The reason is that the wavelength of X-ray radiation can be made 10-30 times less than a nanometer, which makes it possible to obtain very precise data on the nanostructure. However, the run-of-the mill lab equipment is not fit for this kind of work as it may be new but obsolete in terms of both technical parameters and analytical capabilities, and fails to provide bright enough radiation from sources based on the conventional X-ray tubes whose efficiency is less than 1%, that is, worse than that of a filament light bulb. And yet, the brightness of a source is the main prerequisite for the methods of X-ray radiation focusing which alone make it possible to perform measurements of nanostructures. As a consequence, for a researcher to do the necessary measurements, they have to take their sample to where there is a facility  providing X-ray radiation with very high intensity. That is, the researcher has to visit a synchrotron, a unique modern machine designed to produce high-tech test data and knowledge!

    Although there are over fifty synchrotrons in operation throughout the world, only five or six of them are really efficient and valued by scientists. For instance, Grenoble (France) houses the best European synchrotron (which Russia has recently entered as a 6 % co-investor.)

 

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The European synchrotron, ESRF, in Grenoble (France).
Length of the storage ring: 844 m,  energy of electrons: — 6 GEV
(Photo: P. Ginter, ESRF)

 

    The efficiency index of a synchrotron is determined as the ratio of the number of publications to the amount of means spent. The Grenoble research center’s closest rival has an index that is twice lower, while the others fall even farther behind. That about covers it, actually. Scientists representing a host of lines of research from all the developed and many developing countries struggle to get here to perform their measurements. A sort of traffic jam emerges in the very mainstream of the world’s technological progress. We are talking about this "sci-tech traffic jam" and a solution to it with A.G. Turiyanskiy, a Russian scientist, Doctor of Mathematics and Physics, Head of the X-ray Nanostructure Diagnostics Laboratory at the Lebedev Physical Institute of the Russian Academy of Sciences.

 

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Alexander Turiyanskiy (on the left) and Oleg Konovalov (ESRF).
Synchrotron beamline TROIKA, ESRF, Grenoble

 

    — Professor Turiyanskiy, to plunge into physics a bit, could you tell us what a synchrotron is about?

    — A synchrotron is an accelerator of electrons. Typically, it is a complex of two specialized accelerators and a storage ring into which bunches of electrons are injected by the accelerator. The ring has a very large diameter, about the size of a football pitch, and the electrons move along it at a speed that is close to the speed of light. There is no scattering of the bunch particles, though, because ultra-high vacuum is maintained within the installation. Bunches of electrons can be contained in such a ring for days, until the synchrotron changes its mode of operation.

    However, the installation is a ring in appearance only; actually, it is a large polygon, and the distinction is essential in this context. After moving along a considerable stretch of a straight-line path, the electrons turn by a slight angle. The turn does not occur of its own accord; rather, it is effected by bending magnets. The purpose of such a design is that at the turning, the electrons experience acceleration — namely, the acceleration due to the change in direction — and emit a bunch of photons. That exactly is how intensive generation of X-ray radiation works. That is what it is all about, the source.

    Now, for the researchers to be able to make use of this source, special measurement apparatus is installed at this spot — an autonomous user’s experimental station, or, in the language of physicists, beamline.

    Today, the most known to the public is the Large Hadron Collider at CERN (Switzerland) with the ring length of 26.7 km, where the famous Higgs boson has been recently discovered.

    The annual budget of a major synchrotron is over a hundred million dollars, that is, more than the scientific research budget of a medium country. To some extent though, it is refunded by the guest users’ paying for the synchrotron time which is not at all cheap.

    A synchrotron is the brightest source of X-ray radiation. To be precise, a still brighter source has been provided recently by a X-ray free-electron laser at Stanford (USA), but we are not talking of that here. Also, some advanced countries have moved on to the third generation synchrotrons in which large groups (dozens or even hundreds) of bending magnets are built in on straight-line stretches of the electron’s path. Called ‘undulators’, they increase the brightness of a synchrotron beam by several orders of magnitude. The X-ray radiation from an undulator is channeled into a beamline. Electrons are not lost in an undulator, but rather directed by a magnet to a neighboring site where another undulator generates radiation into another beamline. And so on, all along the ring. Of course, electrons lose some of their energy when passing through an undulator. The losses are compensated by a special device installed on the ring. Let us not go into technical details here, though. Suffice it to say that a synchrotron operates in this way round the clock. By the way, it is the quiet night hours that are most popular with the researchers. There is an optimal synchrotron brightness for every scientific problem; accordingly, the synchrotron is set in operation in a definite regime to produce a specified number of electron bunches with specified energy and specified distance between them. The researchers are trying to fit in with the regime that is optimal for their individual problem.

    But alas, it is difficult to gain access to a well-equipped beamline; in fact, a source is out of reach for many. A huge gap has emerged between the demand for high-tech X-ray analytics and the supply of it. On the best beamlines, only one out of every five or six competing applications for synchrotron time is satisfied, while many researchers do not even bother to put in an application because they realize the futility of it.

 

    — Suppose I am an ordinary user. Tell me what difficulties I face.

   — You are to put in an application for a beamline, which means that you have to squeeze considerable money out of the administration of your research institution, as each synchrotron beamline shift, that is, 8 hours, typically costs 4 thousand euros, and for a serious project, you probably need a week, plus travelling and accommodation expenses. Then you have to get an entry visa for the country where the synchrotron is located. Another major problem is that you are not able to accomplish your research on a synchrotron beamline without some serious scientific and technical support from its staff. Also, already on the spot, you usually discover that you need some additional contraptions without which your apparatus does not fit in, etc. (Fortunately, say, the Grenoble synchrotron has its own powerful design office which will make you — for a charge, of course! — the right contraption in a matter of a few days.) Hence, recommendation: before even submitting an application, you should arrive at the beamline in person and talk it all over in detail with the specialists. The expert board will consider your application — not within a week but rather give you time within seven or eight months — and the result will quite probably be zero. The reason is that most users do not have enough experience to write a good project which will be approved by the expert board. Ergo, your project will be declined on “formal grounds”. Things look even bleaker for young specialists who cannot realistically get an OK for their project from the beamline, and anyway, are unlikely to raise the money for their enterprise.

    What we have here is a series of hurdles which block the access to the cutting edge technologies for a wide circle of specialists.

 

    — Can you still squirm your way onto a synchrotron beamline by going through a backdoor, so to say?

    — Yes, such a chance exists, but it is rather slim. You can play this card if your project or idea is on the very forefront of science. The matter is, the best synchrotrons have a well-thought-out and strictly followed scientific and technical policy, and the head of each beamline is under pressure from the synchrotron’s administration to carry out an upgrade (i.e. equipment modernization) within the next few years while the “ideology” of the upgrade is to be announced in advance. For that reason, beamline heads tend to take a serious interest in any directions of research that can be potentially beneficial to their beamline, and in such cases, they can grant a researcher access to the beamline out of turn, during the time scheduled for maintenance and adjustment works. Such joint “backdoor” effort often proves very useful. In this way, it may be possible to overcome quickly the bureaucratic barriers and solve another serious problem haunting every synchrotron center — the problem of confidentiality. If you have a new, original idea, you are required first to expound it in detail in a project for the expert board. With luck, the synchrotron time will be allocated to you in 7-8 months, and possibly, your idea will have been tested by someone else before that. Alas, research ethics is not always adhered to. Still, of course, the “backdoor” approach cannot be considered as a regular solution. If you mean to conduct some standard research, the rules are very rigid — stand in line, please!

 

    — Possibly, things are going to improve soon? Maybe, new synchrotrons are going to be built?

    —  No, things are not going to change for the better in the nearest future, as the advanced countries plan to channel the experimental base development funds to the building of new powerful femtosecond sources — free electron X-ray lasers with an estimated cost to the user of one shift of about 100 thousand dollars and waiting time up to two years. So, the ultra-modern laser beamlines will be even less accessible.

 

    — So, the prospect of building those monsters, "free electron X-ray lasers", does not make the solution that you propose any less urgent?

    — On the contrary, it is becoming all the more urgent. By the way, I took an active part in the working-level discussions on the building of a European free electron X-ray laser. It is a gigantic project with a current estimated cost of 1.2 billion euros, financed by twelve countries, where one half of the funds is put up by Germany, one quarter by Russia, and one quarter by the other participants. Thus, Russia is a major player. This femtosecond X-ray source will allow to solve unique problems. Because the pulse duration on a X-ray laser is a thousand times shorter than that on an existing synchrotron, a major breakthrough in the analysis of fast processes is due. Yet humanity cannot do without that kind of research as fast processes are terra incognita to us yet — we just do not have any notion of how many of them occur while they are the key to understanding fundamental phenomena in physics and chemistry.

    Why then in the working-level discussions, if in the lobbies, pessimism has been voiced about the European project? The simple reason is that the project is going to be the third of its kind, as the American one is already in operation, and currently, a Japanese free-electron laser is being launched. A huge volume of diverse programs and investigations have been planned for them and are already in progress. Thus, the researchers who are the first to work on them will be able to cream off the most exciting, high-priority scientific problems, and by the time the European project is put in operation, many of them will have been solved. I have cited this example to emphasize the point that is key to us here: the replicating strategy programs you for lagging behind!

 

    — But if you are lagging behind already, then you are doomed to follow the leaders, and replication is your only choice, isn’t it?

    — Not at all. You can take another route. Let me illustrate it using a today’s example. Currently, the European project of a linear accelerator for an X-ray laser which two kilometers long is in a final phase of construction. The Japanese, whom we had not taken seriously, claimed they were going to design a linear accelerator less than one kilometer long. The German side just shrugged it off: what if it is not going to work out? It would be a pure waste of money. No, thank you, they said. We would rather stick to our kilometers but have guaranteed characteristics as a result. What happened was that the Japanese spent less money to build and launch a beamline which is shorter than what is provided for by the European project. As a consequence, if a new project is initiated tomorrow, it is the Japanese project rather than the European one that will be assumed as a basis, which implies that it will not be feasible at all without the participation of the Japanese who will dictate everything, from A to Z. More likely still, having gained experience on their beamline, the Japanese will find new scientific and technical solutions and take another major step forward.

 

    — It appears, we have digressed from the synchrotron talk and indulged in criticizing the national scientific research policies...

    — It is no digression; rather, it is the point of the matter. Formerly, as major federal programs by objectives were made up, the Russian science policies were focused on solving this or that problem at a minimum cost. That was a very narrow approach. What we have now is another extreme: the size of a project and the amount of resources involved are considered as its main merit, that is, now we are talking megaprojects. Of course, it is also a one-sided, faulty approach unless it is based on domestic, cutting-edge technologies. The logic of megaprojects aimed at replicating the most advanced current solutions spells obsolescence! The fact is, the leading research centers in the USA, Europe and Japan has gone so far ahead that it does not make sense trying to follow them. Take the Grenoble synchrotron; it is a most complex center of science and technology which we have no chances of catching up with. And we should not try, either. Since Russia has become a participant of the Grenoble consortium, we should work and do the upgrading on the existing beamlines. As for the policy that professes building and implementing similar megaprojects — it is nothing but wasting huge sums of money, in fact, invested in obsolescence! While we believe that we are creating world class systems, we are not only going to get there 10 years late, but also we actually have no chance of reaching the world class, because those systems are upgraded every year and thus become more and more advanced.

 

    — Back to the synchrotron “traffic jam”: do they make any attempts to build a X-ray radiation source on some new principles?

    — Yes, rotating anode X-ray generators have recently come into being which allow to increase the brightness of the X-ray radiation several times, or sometimes, by an order of magnitude. As lab equipment goes, they are quite accessible in monetary terms. But alas, these new generators have been unable to reach parameters comparable with those of synchrotron sources. And there is a downside, too: the power (up to 20 kW) and water consumed by a generator of this type. I have visited labs with those rotating anode sources. It costs about one million euros, and there are some additional expenses necessary to put in place the right infrastructure. The main question is — what to do with the heat? The water cooling system consumes a bucket per minute, so the consumption of both water and energy is huge. The creators of rotating anode X-ray generators have faced a technical barrier and cannot move any further, while the source they have obtained is not at all the brightest by today’s standards.

 

    — Let us get to your project now.

   — Working on synchrotron beamlines, we have witnessed repeatedly that researchers that are striving to get access to a synchrotron beamline fail to find there what they are after. Sometimes the physical object under investigation is very fragile but the researchers believe that they can only obtain good results on a synchrotron beamline thanks to the unique brightness and intensity of its X-ray radiation. However, on the spot, the researcher may discover that the beamline’s specialists deliberately decrease the intensity of synchrotron radiation a great deal. A paradox? No. The matter is, the detecting equipment which is one of the key elements of a synchrotron beamline is a complex and capricious system, only operable within a certain dynamic range. It is often the case that the detecting system cannot operate in the regime that the user requires — it would simply burn down unless some effective absorbing filters are introduced. Another obvious possible cause is that your object may be radiation-sensitive.

    It turns out that many of the baffled applicants who meet with a refusal on the part of a synchrotron beamline, as well as many of the lucky ones who are admitted, do not really need a synchrotron. What they actually need is equipment with characteristics that fall somewhere in between those of a synchrotron and those of standard laboratory tools; such medium characteristics would be enough to solve the problem at hand. Conclusion: there is urgent need for analytical systems that have X-ray-optical radiation-focusing capabilities similar to those of a synchrotron while being accessible to a wide circle of users.

 

    — Is such equipment in existence?

    — It was not formerly, but it is now. This is what we propose: the Multibeam Analytical X-ray Facility (MAX Facility) — a research system on the basis of a new generation liquid anode X-ray source.

 

    — Please, explain! Is the liquid anode some sort of achievement?

    — A Swedish team took a revolutionary step by giving up the solid anode. The physics of the phenomenon is as follows. Up to now, the anodes used in X-ray tubes have been solid, made of wolfram, copper, rhenium, or molybdenum. The specialists have always struggled with the problem of heating the anode, as high temperature makes it melt. For that reason, the four metals of choice are both high-melting and heat-conducting. The Swedish group put forth a contrary concept where the idea is to work with a liquid metal from the very start, that is, incite X-ray radiation in a liquid jet of metal. A liquid metal is exemplified by gallium; if you hold a piece of it, it will melt in your hand. Also, the gallium vapor pressure is very low, which means that an electron beam can be directed onto a jet of liquid gallium, and the electrons will reach the metal without any scattering. A pump is used to make gallium circulate continuously along a closed contour, passing through a very efficient cooler. This has a remote semblance with the storage ring of a synchrotron; in a synchrotron, it is the electrons that act as the working body, while here, it is the liquid metal jet. In this way, the Swedes managed to create a new, brightest source of a laboratory category. Importantly, it is a microfocus source allowing to use the focusing X-ray optics and increase the X-ray flux in a beam thousands of times.

 

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Microfocus liquid-anode X-ray source MetalJet D2.
On the left: Scheme of beam generation; on the right: general view of the source
(Picture: A.G. Turiyanskiy)

 

    — So, that is their find. Where do you come in then?
— We have good ties with the Swedish company in question, both in terms of business and in terms of research and technology. Although not cheap — the price being several thousand dollars — the source that they offer is quite accessible to universities and research institutes. It is the kind of money that can be raised. However, a consumer has no use for a bare source; rather, they need a research station on its base. That is what the Swedish company is very interested in: our offer to develop such a station!

    To say that such a station is an easy thing to make would be irresponsible bragging. The task requires some tricky scientific and technological solutions. But we are no novices; on the one hand, our laboratory has strong ties with the academic science, and on the other hand, we have expertise in technologies and rich experience of developing experimental equipment which has actually been manufactured and is being exploited successfully in a number of Russian and foreign research centers. Just a month ago, a prototype of the first Russian research center on the basis of a liquid anode source was launched at the Immanuel Kant Baltic Federal University by our team together with the university’s specialists. Thus, we can guarantee launching, within one year, of the first X-ray analytic equipment stations. Moreover, should the need arise, we can bring in specialists with whom we collaborate on the synchrotron beamlines. Importantly, our work marks a qualitative transition to new X-ray analytics where the measurement systems are "smart".

 

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Project of a research center on the basis of a liquid anode X-ray source
(Photo: A.G.Turiyanskiy)

 

    — What? Smarter still?

    — You have no idea how hard it is for users to master modern equipment which they need for measurements. Mind you, we are not talking of physicists only; this also refers to specialists in physical metallurgy, material synthesis, fine technologies, ecological problems, etc. Before even you can start working on your own on a modern diffractometer, you have to do a month’s on-site training for which you probably have no time. What you are not told is that this kind of training does not yet make you a qualified specialist in measurement techniques and the equipment.

    When I say that our measurement systems are going to be "smart", what I mean is that we are developing a system that will be doing almost everything for you in an automatic mode. It will allow a user with a minimum experience to solve problems that formerly could be handled by narrow specialists only. The requirements for users exploiting X-ray equipment are reduced dramatically — you just have to pose your problem in general terms, prepare the sample and mount it with the help of the equipment servicing specialist. The automatics and the data processing software will take care of the rest. Thus, to be a user, you only need to have a general knowledge of the principles of the X-ray diagnostics methods.

    Clearly, this minimization of requirements is very important for the wide circles of researchers who have demand for X-ray analytics today! For instance, both biologists and material physicists are in dire need of high-resolution computer tomography. We suggest that one of the MAX Facility beamlines be made exactly a computer tomography beamline with a unique chemical analysis capability.

 

    — What if a complex research is necessary?

   — The MAX Facility has decisive advantages here. The users of a synchrotron face the following problem. A synchrotron has dozens of beamlines, where each is technically perfect, of course, but if you want to do complex research, you will have to move from one beamline to another. That other beamline will probably have a different design, and some new contraptions will be necessary for you to use it. To make the transition, you dismantle your sample. Located dozens of meters apart, the beamlines are virtually separate, radiation-protected research centers, so the transition cannot be accomplished quickly. This circumstance is especially important when the object of study is a biological structure as the characteristics of such an object vary with time. The biggest problem though is that you will be requested to write a new project justifying the necessity of employing that other beamline.

 

    — Do you propose something to relieve that harassment?

   — Our measuring system is comparatively compact and concentrated around a single source. So, without having to dismantle anything, you can make use of precision electromechanics to pass your sample from one measurement beamline to another. All you have to do is type in instructions on a computer. Honestly, such an opportunity is unique today, and it alone can save a lot of time for the user. The fact is, the researchers working on synchrotrons are used to spend a lot of time on the mounting of their samples and all sorts of adjustment and fitting — for the beam to fall where it should, for the sample to be positioned correctly, etc. Often, that kind of preliminary work takes up most of all the time, leaving little for the measurements themselves.

 

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The first liquid anode two-wave X-ray reflectometry station for the analysis of nanostructures. Project by Lebedev Physics Institute of the Russian Academy of Sciences and Kant Baltic Federal University
(Photo: A.G. Turiyanskiy)

 

    To sum up the advantages of our system, we make it as accessible as possible to specialists that are not engaged professionally in X-ray measurements. We can say with confidence that the number of potential users will multiply — not several times but by orders of magnitude!

 

    — And what about the prices? You have cited some frightening figures...

    — The facility will include several experimental work stations, the cost of building an individual station being 10-15 times lower than that of a similar station in a synchrotron center. The total cost of the facility, by today’s estimate, is going to be 3-6 million dollars, depending on the composition and equipment. It is hardly affordable to an individual laboratory, but it is quite affordable to the leading Russian universities and research institutes. By giving a wide circle of researchers — including young ones, even students! — access to the most advanced experimental equipment, the MAX Facilities will pave way to conducting world class research.

 

    — Have you any conception of how the MAX Facilities are going to disseminate, at least initially?

    — To ensure its progress, any developed country has to develop the experimental base of research. Everyone is faced with the problem of choosing an optimal strategy — whether the necessary experimental equipment should be bought abroad, or produced locally, basing on domestic achievements, or else produced in cooperation with foreign partners. Today, import substitution has become a dominant trend in Russia due to the complications in the international relations. Being an inexpensive substitute for a synchrotron, the MAX Facility is totally in this trend. As to initial steps, a practical interest in creating a world class analytic center on the basis of the MAX Facility has been expressed by the Kazakh-British Technical University (Almaty, Kazakhstan).

    Also, as we all remember, the BRICS countries have agreed on prospects of scientific and technological cooperation this year. Although the focus is on a stable list of approved areas such as nuclear power, nanotechnologies, and non-nuclear, ecological energy, new lines of cooperation will also be written into the programs. In our view, the introduction of the MAX Facility could be logically written in, too, as the MAX Facilities open good prospects to researchers from all the BRICS countries.

    There is a potential for great demand for our system, and most importantly, we can be leaders here today. We expect the authoritative government bodies to take interest in our proposals and hold specialist meetings, to be followed by concrete decisions and actions.

 

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The first experimental results of measuring a Al2O3 film (90 нм)on a silicon substrate, obtained by the method of relative X-ray reflectometry on a source with a liquid Ga-anode. Results obtained by research staff members of the X-ray Nanostructure Diagnostics Laboratory and I. Kant Baltic Federal University  S. Gizha and S. Medvedeva
(Picture: A.G. Turiyanskiy)

 

Interview taken by Sergey Sharakshane

Translation by Alexander Sharakshane

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