“I am very nervous,” began D. Bessas on Monday, before the International Conference for the Applications of the Mössbauer Effect 2013, Opatija, “because I stand before Mössbauer spectrometers” [scary, methinks, in and of itself] “and I will not talk about Mössbauer and I will not talk about iron.”
“…Actually,” he went on to clarify a little later on, “there is a connection between Nuclear Inelastic Scattering and Mössbauer spectroscopy, otherwise there would be no reason for me to be here.”
But for very subject specific conferences like this, that is always the case. I spoke about chemistry and the application of Mössbauer to assist environmental research; across the week, others have spoken about geology, quantum physics and biological processes. And in all of these research threads, the common application of Mössbauer spectroscopy or similar effects has persisted. Our elucidations have ranged from the poignant to the absurd;
“The high spin to low spin transition can profoundly affect the structural, magnetic and electronic properties of this material and thereby influence our understanding of the earth’s core,” says I.S. Lyubutin: understanding very small local changes in materials can have big consequences to our world view. He refers to his work as the “spin chicken and egg problem”, by the way.
What is Mössbauer spectroscopy?
Well, for the unenlightened, Mössbauer spectroscopy is an analytical technique which works by the application of gamma rays to probe nuclear energy levels, which process gives information about the local environment around a Mössbauer-active centre (usually iron. I work with iron. Iron is good). I’m a chemist, so I use it to learn about my products. Or, as F. Berry said, “Chemists make things. Chemists make new things. And that’s the central principle to the practice of chemistry.” For others, Mössbauer spectroscopy is useful for solving Einstein’s clock problem (trying to discover whether there’s a limit on acceleration in nature), or they are piloting synchrotron Mössbauer spectroscopy.
Frank Berry’s comment makes another “observation” however: we are all scientists, but we are not all the same kinds of scientists. “I think this is the fight between chemists and physicists, for whatever reason,” says W. R. Scheidt. He’s being flippant, but he sounds a little wary all the same. “Yes [this work] is very complex physics,” H. P. Gunnlaugsson acknowledges to his very varied audience. And jokes, “I will now spend the next two hours explaining.” Whilst I’m sure we’re all very relieved he didn’t, “we all know that Mössbauer spectroscopy is very useful,” even though we value it in different ways, so there is an element of “preaching to the choir,” as D.H. Ryan puts it, and we do have some similar approaches.
“Now, if we had a neutron audience here, most people would start to panic when they saw this slide,” says J. M. Cadogan as he expounds his neutron research on gadolinium compounds. We stare blankly. But we are appreciative of the subterfuge of J. Lindén, who complains, “Now, if you present hyperfine parameters to non-Mössbauer spectroscopists, they will either be bored or angry. So we have to do something clever.” And nobody so much as blinks when he personifies functions: “whenever there’s a Hamiltonian hanging around that nature can use, it will use it.”
Even more crucially, it’s important to remember that this is a mobile community; because the mutual field is an analytical technique, rather, say, than a series of related chemical compounds, it is more likely that several members will dip in and out of Mössbauer spectroscopy during their research careers. Mössbauer himself had moved out of the field by the time he died in 2011. We are like antimony, as F. Berry describes it in an answer to a question about synthesis methods: “There are some materials which we use that are very mobile… You try heating antimony in a lab in an open crucible and there’s antimony up the walls – it just goes everywhere!” And so do Mössbauer spectroscopists. We go all over research.
[And last night, all over the dance floor]
And after eighty talks and two hundred and twenty-one posters, I’m pretty tired of Mössbauer spectroscopy. The energy this week has been incredible, especially when it came to controversial research. “Lively discussion is very important for this conference, but now we must continue,” insists chair G. Wortmann after a heated debate on the interpretation of Mössbauer spectra of FeSe and related superconducting compounds. Men were actually getting out of their seats to shout across the room, forming, for me, a low rumble of accented English words, bubbling over each other. Over two talks on this subject, we ran 20 minutes late: roughly half the combined lengths of the talks. The debate was carried into coffee time, highlighting the passion and enthusiasm of so many scientists to percolate the “right” view through the research community as theories evolve and camps of opinion develop.
Which is, of course, how science works: it is an idea or theory pool, where its dedicated practitioners devote themselves to substantiating their perspective. But we have to try to keep an open mind, and it’s too easy to make assumptions; E. Bill warns us on the dangers of research theory: “Is it valid to talk about iron oxidation states…?” he asks. And adds ominously, “We are deep in metal organic chemistry.” And none of us, I think, want to go there.
“Maybe we should start with a coffee break,” suggests chair K. Schlage, whilst J. M. Cadogan struggles with “the joys of Mac versus Windows.”
But when it comes to mistakes, misappropriated theories and practices, none are so good an example as D. H. Ryan’s talk on Moments, fields and magnetismin Eu-based EuTM2X2 compounds, which he subtitled “A cautionary tale.”
He starts by talking about gathering his data at a neutron source, and how they responded to nuclear disaster. “Because this was the fifties and they liked nuclear power back then, they rebuilt it and thought if they put a couple of extra things in place, we can put in a bigger core, rather than scrapping it and walking away from nuclear power for the rest of their lives,” he says, and even though it is integral to his research, there is a certain exasperation in his tone as he reflects on the basis of this decision.
He also has comments on the interface between teaching and research: “If a student gets an answer which is out by an order of magnitude, we typically say that’s wrong. So we should really say this is wrong.” “This”, by the way, is the basis of his research, from which he concludes firmly, “It doesn’t work for iron; it never really has… It doesn’t work for tin… And it doesn’t work for europium. Perhaps we should just stop claiming that the hyperfine field tells us what the moment is.”
[this post may also be found on my RSC blog]