Music, Maths, and Mash-Ups

It’s been a huge pleasure and a lot of fun to host Esa Räsänen and George Datseris here at Nottingham over the last few days. Once the video of George’s seminar, “Music Time Series Analysis: Universal Structure and Its Impact on the Listening Experience“, is edited and uploaded, I’ll write a longer post expanding on Esa’s and George’s work and the reasons why they both spent some time visiting our group at Nottingham. (I’ve been following Esa’s work for quite some time now…)

In between our discussions of 1/f noise, microtiming deviations, and power spectra, Esa introduced me to some classic compositions in the “mash-up” genre, of which I was previously only vaguely familiar. That meant that I was missing out on gems like this ground-breaking Bangles-Slayer collaboration…

Thank you, Esa, for expanding my musical horizons!

More soon on the physics behind Esa and George’s visit, but for now I’ll leave you with George’s wonderfully monikered (and logo-ed) band, The Max Funk Institute. George, a professional drummer, has recently completed his PhD at, you guessed it, the Max Planck Institute. He’s clearly a polymath; music, physics, and — as the first few seconds of the video below show — acting all fall within his sphere of expertise….

Taking the Pain out of Probes*

* I have unashamedly stolen this title from my friend and erstwhile colleague at Nottingham, Richard Woolley. Rich, I hope you’ll forgive the plagiarism.  

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Scanning probe microscopy is my first love when it comes to experimental science. Although I’ve spent quite a bit of time at synchrotrons over the years, I still turn to SPM first and foremost when it comes to probing the structure of matter. After all, what other technique allows us to not only see single atoms and molecules, but to interrogate them mercilessly, reaching down to the level of individual chemical bonds, and pick, prod, push, and/or pull them around a surface? What other technique enables us to capture not only the electronic structure (both filled and empty states in a single “shot”), but the vibrational “wobbles”, the potential energy landscape (of various forms), the probability density, and even the magnetic signature of a single atom or molecule (in parallel, and with energy resolutions that are in essence only thermally limited)?

And, as I suspect my fellow probe microscopists would heartily agree, what other technique is quite so damn irritating, fist-clenchingly frustrating, and hair-pullingly maddening at times?

Probe microscopists can spend hours, days, or sometimes even weeks trying to cajole the component at the very core of the microscope — the tip (or, more precisely, the atomistic structure at the very apex of the tip) — into behaving itself. We use a variety of recipes to modify the tip apex, ranging from rather gentle and delicate indentations (pushing the probe a few angstroms into the surface), picking up a molecule, or rather “tame” voltage pulses of a few volts… to plunging in, burying the probe, and ploughing a furrow across the substrate. And then we scan and hope to see atomic resolution. But even if we see atoms, it mightn’t be the right type of atomic resolution [1]. We might have a double tip (i.e. two atoms are involved in forming the image), or a triple tip, or, something else entirely

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Those images above are all of the atomic structure of the Si(100) surface (as described in this video, and as sketched in the top right corner of the slide, where we’re looking down on the surface. Large circles represent atoms that are “buckled” out of the surface, creating a zig-zag pattern — technically, a c(4×2) reconstruction — of non-planar pairs of atoms (dimers).) In each case, the surface has the same atomic structure — the variations from image to image are purely tip-related. And if we find the tip in a state that doesn’t give us the image we expect or need [2] then we crash, or hammer, or pulse, or bash, and swear repeatedly until we get what we want. Sometimes — usually around five minutes to lunchtime, or 5 pm on a Friday evening — the tip gets better. Other times it gets much, much worse. So we sit there for hours, trying to recover the tip. Or we change it for a new one. And then try to coerce that into showing us atoms, or more than atoms.

But we don’t need to suffer like this. There is a better way. And finding that lower — and hopefully minimum — frustration pathway to better probe microscopy was the subject of a meeting at the Institute of Physics on Friday. Organised by Martin Castell (Oxford) and myself, the theme of the meeting was machine learning for atomic resolution scanning tunnelling mcirscopy (STM) and atomic force microscopy (AFM.) In attendance were scientists from across the UK who each wanted to move our field forward so as to take the pain away (and, of course, consequently do rather more interesting experiments/theoretical calculations as well.) Oxford, Nottingham, King’s College London, Newcastle, Loughborough, University College London, Warwick, Liverpool Physics, St. Andrews, and Swansea were each represented on the day, with apologies from SPM researchers at Bath, Lancaster, Leeds, Liverpool Chemistry, and Cambridge (who were still keen to be involved but were unfortunately otherwise engaged.)

One striking statistic that was very evident when putting together a list of invitees for the meeting was that the ultrahigh vacuum/atomic resolution scanning probe community in the UK is rather skewed towards blokes of “a certain age” (and that most definitely includes me.) It’s been suggested — by Eugenie Hunsicker (Loughborough) — that one way to attempt to address this would be to consider a collaborative incubator project, a scheme funded by the University of Bath’s Inclusion Matters programme. (Nottingham is also an Inclusion Matters grant-holder.) That is definitely a funding strategy I, for one, would like to pursue, alongside other EPSRC networking opportunities.

My slides for the meeting are embedded below. I will add the PowerPoint/pdf files for the other presenters, if and when I get permission, at the foot of this post. (Giovanni Costantini (Warwick) has already given me permission so his slides are the first there.) The core motivation for the meeting was to bring as many probe microscopists as possible together — and perhaps choosing the last working day before the start of the new academic year for many was slightly ill-advised from that perspective — to discuss strategies for ensuring that we don’t spend a lot of time “reinventing the wheel” when it comes to developing machine learning protocols. And our main objective is therefore to put together a UK-wide network of groups working on the machine-learning-enabled probe microscopy theme.

Despite the prevailing ‘wisdom’ in some deluded corners, the UK of course can’t stand alone, isolated and insular, when it comes to scientific research (or anything else for that matter.) Science is inherently international in scope, and the vast majority of research in this fair and sceptred isle thrives on collaborative activities with our colleagues outside the UK.  When it comes to machine learning in scanning probe microscopy and nanoscience, in particular, we need to pay especially close attention to the exceptionally exciting and pioneering work being done by a number of groups across the world.

Some of those key groups are listed in the PowerPoint slides embedded above, including Bob Wolkow’s research team at the University of Alberta. Bob and his colleagues are very much setting the bar for the rest of us — particularly those of us who work extensively with silicon surfaces — when it comes to embedding machine learning in not just atomic resolution imaging but single atom manipulation. As Bob describes in this engaging TEDx video (uploaded just a few days ago), the STM (“See, Touch, Move”) is becoming ever more capable; one key advance that Bob’s group — in particular, PhD student researcher Taleana Huff and her colleagues — has made is the ability to repair/edit single atomic defects[3] :

Watch the video to get an insight into just how far the UoA team have pushed forward the state of the art in what is effectively 3D printing with atoms. Bob suggests that the latest advances from his group are potentially as disruptive as the transistor was to the vacuum tube. I’d cautiously agree with that statement, although moving from a UHV low temperature environment to the “big, bad world” outside the vacuum chamber is always going to be fraught with difficulty. I am looking forward immensely to spending a couple of weeks at UoA next year to learn more about the techniques pioneered there, thanks to funding from both UoA and Nottingham’s International Collaboration Fund.

I’ll provide updates on how the machine learning SPM network is progressing in future blog posts. For now, here are the slides from Giovanni, as promised above, and from Oli Gordon (Nottingham). (Oli is also pictured in the image that kicks off this post.)

Update 07:47 26/09/2019 It was hugely remiss of me not to highlight a very important upcoming (Jan 2020) conference in Kanazawa — The First International Conference on Big Data and Machine Learning in Microscopy. My sincere apologies to the organisers — sorry, Adam et al. — for not including this in the original post.


Presentations

Molecular-Scale Surface Analytics — Giovanni Costantini (Warwick)

Scanning Probe Tip State Recognition in Real-Time with Neural Networks — Oliver Gordon (Nottingham)

Machine Learning and (SI)STM — Peter Wahl (St. Andrews)

See also ““Nanoscale electronic inhomogeneity in FeSe0:4Te0:6 revealed through unsupervised machine learning”, P. Wahl et al. (submitted)

Multi-scale Computation in Nature: exploring the Interface between Computing, Synthetic Biology and Nanotechnology — Nat Krasnogor (Newcastle)


[1] …and how do we know what’s the right type of atomic resolution? That’s very much a moot point. Sometimes it’s whether the microscopist sees the same type of image as other groups have published previously. This is a slightly worrying way to do science.

[2] Note that we may not always want the highest possible spatial resolution. Different tip structures can have different densities of states, for one thing, and this can affect their ability to extract or move atoms (or molecules).

[3] Not that we’re bitter or anything, but an alumnus of the group, Peter Sharp, tried for very many months, years ago as part of his PhD, to get enough reproducibility to routinely “heal” single atom — more precisely, single dangling bond — defects in the manner that Taleana and her colleagues in Wolkow’s team have achieved. While Pete could definitely observe dangling bonds disappearing during a scan (see below — captured from Pete’s PhD thesis via my phone), which we interpreted as a transfer of a H atom from the tip, we could never quite get the transfer to happen reliably via chemomechanical force alone when we targetted a single dangling bond.

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“Remember Your Humanity”

Thoughts about the upcoming Ethical Science conference at the School of Physics and Astronomy, University of Nottingham on 23rd October 2019.

This is a guest post from Andrew Gibson, Coordinator of Student/Young Pugwash UK and a University of Nottingham alumnus, about an important upcoming conference that the School of Physics & Astronomy is hosting. 


“Remember your humanity, and forget the rest”

These were the words of Sir Joseph Rotblat, the nuclear physicist, in his speech while collecting the Nobel Prize for Peace in 1995. Rotblat was the founder of the Pugwash Conferences on Science and World Affairs, an international grouping of scientists who seek to use their expertise and standing to resolve the most serious international security problems. It is believed that research and ideas produced by this group, such as at their biennial international conferences, has directly contributed to the development of the Partial Test Ban Treaty (1963), the nuclear Non-Proliferation Treaty (1968) and the Chemical Weapons Convention (1993). Formed at the start of the Cold War, the Pugwash Conferences encouraged scientists to think beyond East-West divisions and to consider the ethical consequences of their work.

But what about today’s problems? What would Rotblat have to say about the ubiquity of digital technology, the widespread use of drones, and the challenge of climate change?

These are the questions we will consider at a conference organised by Student/Young Pugwash (SYP) UK on 23rd October, in partnership with UoN PhysicsUoN Physics.

One session will consider proposals for a ‘Hippocratic Oath for Scientists’. In a 1999 article for Science (here), Rotblat argued for such an Oath, which would be a public promise to consider the ethical implications of one’s research and career. This call was recently echoed by UCL’s Dr Hannah Fry, who called for a Hippocratic Oath for computer scientists in an era of Cambridge Analytica and ‘killer robots’. What do you think?

Another session will hear from Laura Nolan, a former Google employee who resigned in protest about the company’s involvement in Project Maven, a US DoD initiative to use artificial intelligence technology to analyse drone surveillance footage. Another speaker will be Dr Ian Crossland, a nuclear waste specialist, who will consider the role of ‘intergenerational ethics’ in decision-making within the nuclear industry.

We welcome people of all ages, disciplines and ideologies to the upcoming Ethical Science conference on 23rd October at University Park, Nottingham. Bring your ideas, feel free to argue but always… remember your humanity.

Programme and registration is online here

The One That Got Away…

This is a guest post from Mo Beshr, an undergraduate student at TU Dublin who’ll soon be starting the final year of his Science with Nanotechnology degree. As part of his third year programme, Mo spent six months — from March until August — in our group. [Note to group: we really need to update our website.] Mo’s thoughts on his internship are below. The best of luck with your final year, Mo!


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I knew from before even starting university that I wanted to pursue a career in research as it’s been a long-time dream of mine to make a difference in the world — what better way is there than being on the forefront of science discovering something new every day! All students in my course were given the opportunity to carry out their placement in Ireland or abroad through the Erasmus programme. It was always a goal of mine to travel abroad and experience what it would be like to live independently. So once my supervisor at TU Dublin approached me about placement opportunities, I made it clear to him that I was keen to travel abroad.

I was offered countless research opportunities in various universities across Europe such as Germany, Switzerland and France. I’m not much of a languages guy, however, so I thought I’d give living in Nottingham in England a go; sure, they’re our neighbours from across the pond. But if we’re going to be serious, I immediately jumped at the idea of carrying out my placement in the University of Nottingham as I knew a lot about it through watching Sixty Symbols, Numberphile, and Periodic Videos on YouTube, which are channels that include videos on various topics in science explained by staff members of the university. As well as that, I had known of the great work carried out by the Nanoscience Group at the University and I was very excited to see how all that I had studied as a Nanoscience undergrad was applied. Thankfully I was accepted to carry out my work placement in the University of Nottingham working directly with the Nanoscience Group under the supervision of Professor Philip Moriarty between March and August 2019.

My work was focused on the use of ultrahigh vacuum, low temperature ( 5 K and 77 K) scanning tunnelling microscopy (STM) for atomic resolution imaging of metal and semiconductor surfaces, spectroscopy and manipulation of single atoms and molecules. As you can imagine, going from being a goofy student who attended a handful of lectures everyday to being thrown into the big bad world of research was quite daunting. However, with some time and excellent help and advice by the PhD researchers I worked with and my supervisor I got into the swing of things quickly.

Initially, the toughest tasks were understanding how the STM system I would be using operated and how to analyse STM images and spectra. During my initial time in Nottingham I worked with a PhD researcher named Alex Allen on his project, which involved taking scanning tunnelling spectra (STS) of a C60/ Ag(100) sample using the Createc low temperature STM system. When I had first arrived, a sample of C60/Ag(100) had already been inside the Createc STM chamber and only ever removed for annealing and deposition purposes. During one of our weekly meetings, Phil noticed there were porphyrin contaminants on our sample and in order to fix this we had to remove the sample first from the STM and then from the ultrahigh vacuum chamber. While doing this we were, of course, always observing the movements of the STM tip using the live video from the camera. We then replaced the sample.

Once cleaning of the sample had been completed (by sputtering with ions and subsequent annealing), we would bring the sample back into the STM chamber and scan it in order to make sure it was clean and had an atomically flat surface; on the final sputter-anneal cycle, we achieved atomic resolution. Deposition of the desired molecules would then take place. The deposition process involved placing the sample over a crucible of C60. The crucible was then heated up with a high current which in turn sublimes the buckminsterfullerene molecules, thus allowing for the molecules to impinge on the surface of the sample. Once deposition was complete, we collected liquid nitrogen — following my health and safety induction — and then pumped it through the manipulator arm. This was done in order to cool the sample and control just how the fullerene molecules crystallised on the surface.

Finally, the sample was returned to the STM and scanning commenced once again. The  cryostat surrounding the STM was regularly filled with liquid nitrogen, which keeps the sample cooled throughout the scans…

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In quite a few cases the scans were quite blurry or appeared smeared due to the STM tip being in a bad state. Sometimes the tip wasn’t atomically sharp and/or add more than one molecule on its apex, leading to multiple tunnelling current centres and thus “blurring” the image. In that case, a method known technically as, err, “crashing” was implemented — a clean area was found, and the tip was pushed into the surface to modify its apex. Once a tip had been “sharpened” and clear images were produced, we could carry out scanning tunnelling spectroscopy (STS) of the surface at any specific point. The tip would be positioned above a molecule. The bias was then varied, and the tunnelling current was recorded, giving a plot of the current-voltage characteristic for a single molecule. Differentiating the I(V) spectrum gives us information on the density of states of the molecules.

As well as gaining valuable experience in operating STM systems, I also obtained training in so-called “soft” skills. Literature review topics were assigned to me prior to carrying out any experimental work so I would have a better understanding of the topic of investigation. This involved me writing a report summarising the literature on that topic. The reviews were an excellent opportunity for me to improve my academic writing skills; with every review I could see improvement, and this prepared me very well for my end-of-placement report. After each literature review, I presented what I had found during group meetings, which was very intimidating as I had never given a presentation before! However, I improved with every presentation and the practice gave me great confidence when I returned to Ireland to present my work placement experience to my peers and lecturers.

Completing my work placement with the Nanoscience Group at Nottingham has let me  apply what I have learned in my three years as an undergraduate student and really opened my eyes to a future in research and academia. I now understand what it takes to be a researcher and I believe that I am now capable of pursuing my dream of becoming a researcher and hopefully to make a positive impact in the world of science. I hope this blog inspires other students like me to consider research as a future career path, as there is truly so much still out there to learn and find out. One tends to learn something new every day, and you realise that you are indeed on the frontline of science.

Guilty Confessions of a REFeree

#4 of an occasional series

At the start of this week I spent a day in a room in a university somewhat north of Nottingham with a stack of research papers and a pile of grading sheets. Along with a fellow physicist from a different university (located even further north of Nottingham), I had been asked to act as an external reviewer for the department’s mock REF assessment.

I found it a deeply uncomfortable experience. My discomfort had nothing to do, of course, with our wonderfully genial hosts — thank you all for the hospitality, the conversation, the professionalism, and, of course, lunch. But I’ve vented my spleen previously on the lack of consistency in mock REF ratings (it’s been the most-viewed post at Symptoms… since I resurrected the blog in June last year) and I agreed to participate in the mock assessment so I could see for myself how the process works in practice.

Overall, I’d say that the degree of agreement on “star ratings” before moderation of my co-marker’s grading and mine was at the 70% level, give or take. This is in line with the consistency we observed at Nottingham for independent reviewers in Physics and is therefore, at least, somewhat encouraging. (Other units of assessment for Nottingham’s mock REF review had only 50% agreement.)  But what set my teeth on edge for a not-insignificant number of papers — including quite a few of those on which my gradings agreed with those of my co-marker — was that I simply did not feel at all  qualified to comment.

Even though I’m a condensed matter physicist and we were asked to assess condensed matter physics papers, I simply don’t have the necessary level of hubris to pretend that I can expertly assess any paper in any CMP sub-field. The question that went through my head repeatedly was “If I got this paper from Physical Review Letters (or Phys. Rev. B, or Nature, or Nature Comms, or Advanced Materials, or J. Phys. Chem. C…etc…) would I accept the reviewing invitation or would I decline, telling them it was out of my field of expertise?”  And for the majority of papers the answer to that question was a resounding “I’d decline the invitation.”

So if a paper I was asked to review wasn’t in my (sub-)field of expertise, how did I gauge its reception in the relevant scientific community?

I can’t quite believe I’m admitting this, given my severe misgivings about citation metrics, but, yes, I held my nose and turned to Web of Science. And citation metrics also played a role in the decisions my co-marker made, and in our moderation. This, despite the fact that we had no way of normalising those metrics to the prevailing citation culture of each sub-field, nor of ranking the quality as distinct from the impact of each paper. (One of my absolutely favourite papers of all time – a truly elegant and pioneering piece of work – has picked up a surprisingly low number of citations, as compared to much more pedestrian work in the field.)

Only when I had to face a stack of papers and grade them for myself did I realise just how exceptionally difficult it is to pass numerical judgment on a piece of work in an area that lies outside my rather small sphere of research. I was, of course, asked to comment on publications in condensed matter physics, ostensibly my area of expertise. But that’s a huge field. Not only is no-one a world-leading expert in all areas of condensed matter physics, it’s almost impossible to keep up with developments in our own narrow sub-fields of interest let alone be au fait with the state of the art in all other sub-fields.

So we therefore turn to citations to try to gauge the extent to which a paper has made ripples — or perhaps even sent shockwaves – through a sub-field in which we have no expertise. My co-marker and I are hardly alone in adopting this citation-counting strategy. But that’s of course no excuse — we were relying on exactly the type of pseudoquantitative heuristic that I have criticised in the past and I felt rather “grubby” at the end of the (rather tiring) day. David Colquhoun made the following point time and again in the run up to the last REF  (and well before):

All this shows what is obvious to everyone but bone-headed bean counters. The only way to assess the merit of a paper is to ask a selection of experts in the field.

Nothing else works.

Nothing.

Bibliometrics are a measure of visibility and “clout” in a particular (yet often nebulously defined) research community; they’re not a quantification of scientific quality. Therefore, very many scientists, and this most definitely includes me, have deep misgivings about using citations to judge a paper’s — let alone a scientist’s — worth.

Although I agree with that quote from David above, the problem is that we need to somehow choose the correct “boundary conditions” for each expert; I can have a reasonable level of expertise in one sub-area of a field — say, scanning probe microscopy or self-assembly or semiconductor surface physics — and a distinct lack of working knowledge, let alone expertise, in another sub-area of that self-same field. I could list literally hundreds of topics where I would, in fact, be winging it.

For many years, and because of my deep aversion to simplistic citation-counting and bibliometrics, I’ve been guilty of the type of not-particularly-joined-up thinking that Dorothy Bishop rightly chastises in this tweet…

We can’t trust the bibliometrics in isolation (for all the reasons (and others) that David Colquhoun lays out here), so when it comes to the REF the argument is that we have to supplement the metrics with “quality control” via another round of ostensibly expert peer review. But the problem is that it’s often not expert peer review; I was certainly not an expert in the subject areas of very many of the papers I was asked to judge. And I’ll hold that no-one can be a world-leading expert in every sub-field of a given area of physics (or any other discipline).

So what are the alternatives?

David has suggested that we should, in essence, retire what’s known as the “dual support” system for research funding (see the video embedded below): “…abolish the REF, and give the money to research councils, with precautions to prevent people being fired because their research wasn’t expensive enough.” I have quite some sympathy with that view because the common argument that the so-called QR funding awarded via the REF is used to support “unpopular” areas of research that wouldn’t necessarily be supported by the research councils is not at all compelling (to put it mildly). Universities demonstrably align their funding priorities and programmes very closely with research council strategic areas; they don’t hand out QR money for research that doesn’t fall within their latest Universal Targetified Globalised Research Themes.

Prof. Bishop has a different suggestion for revamping how QR funding is divvied up, which initially (and naively, for the reasons outlined above) I found a little unsettling. My first-hand experience earlier this week with the publication grading methodology used by the REF — albeit in a mock assessment — has made me significantly more comfortable with Dorothy’s strategy:

.”..dispense with the review of quality, and you can obtain similar outcomes by allocating funding at institutional level in relation to research volume”.

Given that grant income is often taken as yet another proxy for research quality, and that there’s a clear Matthew effect (rightly or wrongly) at play in science funding, this correlation between research volume and REF placement is not surprising. As the Times Higher Education article on Dorothy’s proposals went on to quote,

The government should, therefore, consider allocating block funding in proportion to the number of research-active staff at a university because that would shrink the burden on universities and reduce perverse incentives in the system, [Prof Bishop] said.

Before reacting strongly one way or another, I strongly recommend that you take the time to listen to Prof. Bishop eloquently detail her arguments in the video below.

Here’s the final slide of that presentation:

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So much rests on that final point. Ultimately, the immense time and effort devoted to/wasted on the REF boils down to a lack of trust — by government, funding bodies, and, depressingly, often university senior management — that academics cannot motivate themselves without perverse incentives like aiming for a 4* paper. That would be bad enough if we all could agree on what a 4* paper looks like…

Molecules at Surfaces: What do we really know?

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MatsI’m writing this on the Liverpool Lime Street to Norwich train1, heading back after attending an inspiring and entertaining symposium at the University of Liverpool over the past couple of days. As the title of this post suggests, the symposium had molecules at surfaces as its theme. More than that, however, it was a celebration of the work – and often, the life and times — of Prof. Mats Persson (pictured right), a formidably talented, influential, and yet humble and unimposing theorist who has played a leading role in shaping and defining the research fields in which I work: surface science, nanoscience, and, in particular, scanning probe microscopy. The words “A true gentleman” were repeated regularly through the symposium by Mats’ former PhD students researchers, postdocs, and co-workers, for very good reason.

Organised by George Darling, Matthew Dyer, Jackie Parkinson, and Rasmita Raval, the symposium was one of the best meetings I’ve attended not just recently but throughout my career to date. Ras, a leading light in the UK surface science community who has worked closely with Mats since he arrived in Liverpool in 2006 (and with whom I had the pleasure of collaborating on the Giants Of The Infinitesimal project2), kicked off the symposium with an engaging overview of not just surface science at Liverpool but of the city itself, including, of course, mention of the age-old rivalry between the two primary religious factions: the Reds and the Blues3.

What I particularly enjoyed about the meeting was the blend of world-leading science – an accolade that is often thrown around with wild abandon regardless of the quality of the work, but in this case its usage is absolutely justified —  with personal anecdotes about Mats’ career and those of his (very many) collaborators. It brought home to me yet again just how important social dynamics are to the evolution of science, no matter what howls of outrage this suggestion might provoke in certain quarters. Yes, of course, we do our utmost to be as rigorous, objective, and systematic in our research as possible – well, most of us – but the direction of a field is influenced not just by the science but by the “many-body interactions” of those who do the science. (For those interested in finding out more about the extent to which developments in science are influenced by the sociology of scientists, I thoroughly recommend Harry CollinsGravity’s Kiss; it’s that rarity among science and technology studies (STS) books: a page-turner. Harry is going to be visiting Nottingham in a couple of months to give an invited seminar for The Politics, Perception, and Philosophy of Physics module and I’ll post a lot more about his work then (including this fascinating “Spot The Physicist” experiment.))

A great example of just why the “who” can be as important as the “what” was this morning’s thoroughly entertaining retrospective from Stephen Holloway, erstwhile Head of Chemistry at Liverpool. Stephen covered not just his memories of working with Mats but included fascinating anecdotes about the political landscape, the interpersonal conflicts, and the “Big Names” who influenced the evolution of surface science through his career from the seventies onwards. I’ll spare Stephen’s (and others’) blushes by not revealing the names he mentioned, but his stories of scientists not quite being able to put personal grudges behind them when reviewing or assessing the work of their rivals/nemeses is just one aspect of where the personal and the professional are blurred. (This post from the popular blogger Neuroskeptic emphasises just how entwined these dual aspects can be.)

A running gag throughout the symposium was that many of those presenting owed their tenure/academic positions, either directly or indirectly, to working with Mats. And, indeed, the line-up of presenters read like a “Who’s Who?” of the most respected and influential groups in experimental and theoretical surface science/nanoscience today. Highlights are too many to mention but in addition to Stephen Holloway’s opening act this morning, I particularly enjoyed Wilson Ho’s compelling overview of his pioneering inelastic tunnelling spectroscopy work4 which opened the scientific symposium yesterday afternoon; Leonhard Grill’s always-fascinating insights into the reactions, switching and dynamics of single molecules at surfaces (the “ask Mats” image that opens this post is taken from Leonhard’s presentation);  Richard Palmer’s characteristically absorbing overview of his group’s STM and STEM research; Takashi Kumagi’s next-generation nanoplasmonics using sculpted probes…

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…and Jascha Repp’s engrossing presentation of his group’s exceptionally impressive work on combining ultrafast optics with probe microscopy, enabling an unprecedented increase (by very, very many orders of magnitude) in the temporal resolution of the tunnelling microscope. This is Jascha presenting the working principle of the THz-STM:

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…and one of the stand-out moments of the symposium for me was a video of the internal vibrational dynamics of a single adsorbed molecule, captured with ~ 100 femtosecond temporal resolution using the THz-STM technique. There is no question that the exciting results Jascha presented represent a truly ground-breaking step forward in our ability to probe matter at not just the sub-molecular but the sub-Angstrom scale — perhaps not quite as seismic as the Nobel-winning gravitational wave discovery but, nonetheless, an achievement that will certainly cause considerable ripples across the surface science, nanoscience, and scanning probe communities for many years to come.

Two other talks particularly piqued my interest, due to both the fascinating insights into single molecule behaviour and the alignment with my particular research interests right now. Cyrus Hirjibehedin – formerly of UCL and now at Lincoln Lab, MIT (Cyrus’ move back to the other side of the pond is a major loss to the UK scanning probe/nano/surface/magnetism communities) — gave a typically energetic and compelling presentation on his work on probing and tuning magnetic behaviour in phthalocyanine molecules, while Nicolas Lorente, who manages to combine razor-sharp scientific insights with razor-sharp wit in his presentations, discussed fascinating work on the Jahn-Teller effect (I’ll discuss this in a future post), again in phthalocyanine molecules. We are eagerly awaiting delivery and installation of a Unisoku high magnetic field STM/AFM, kindly funded by EPSRC, and so spin will be a major focus of our group’s research at Nottingham in the coming years. We’ve got such a lot of catching up to do…

Finally, it would be remiss of me to close this overlong post without mentioning a prevailing and exceptionally important theme throughout the symposium: the very close interplay between experiment and theory. Almost every speaker highlighted the “feedback loop” between experimental and theoretical data, but it was David Bird of the University of Bath whose — once again, thoroughly engaging — perspective hammered this point home time and again…

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“Experiments Lead The Way”

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“You learn more when theory doesn’t agree with experiment than when it does”, and…

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“Simple models are best.”

This strong and very healthy experiment-theory interplay contrasts somewhat with other fields of physics, where sometimes experimental data seems to be almost an afterthought, at best, in the generation of new theories

A big thank-you to George, Matthew, Ras, and Jackie for organising such a great meeting. And, of course, enjoy your retirement, Mats!


A service that usually runs via Nottingham — cancellations, strikes, and acts of god/God/gods permitting — and with which I’m exceptionally familiar following very many fun, and occasionally somewhat gruelling, beamtime experiments at the now sadly defunct Daresbury Synchrotron Radiation Source. Daresbury is beside Warrington, which in turn is roughly midway between Liverpool and Manchester. I spent a lot of time (up to three months per year) at Daresbury in the late(-ish) nineties to early noughties, with very many hours whiled away sodden and/or freezing on the Warrington station platform, eyeing the announcement board and waiting for trains to collapse from a delayed-cancelled superposition into a more defined state…

2 Our friend and colleague Tom Grimsey, the powerhouse behind the Giants… project, sadly passed away almost five years ago. He was a wonderful man — full of enthusiasm for, and a hunger to learn about, all things nano, molecular, and atomic. I think that Ras would agree that Giants was such a fun project to work on because of the unique perspective Tom and Theo brought to our science. I couldn’t help but wonder a number of times during the symposium what Tom would have made of the incredible single molecule images presented during the talks.

3 Not being a football fan, I can’t comment further. (My dad was a lifelong Sunderland fanatic and my lack of interest in football may possibly not be entirely unrelated to this fact…)

4 …although I don’t quite yet share Wilson’s confidence in scanning probe microscopy’s ability to “see” intermolecular bonds.