Ask a Nobel Laureate and You Have a Good Chance to Receive an Answer

Hello everybody! Last month I was surprised to see an email in my inbox from Rieko Kawabata, Programme Coordinator at Nobelprize.org inviting me to take part into the Ask a Nobel Laureate project, by asking a chemistry question to Professor Harry Kroto, Nobel laureate in 1996 for the discovery of fullerenes. From all the questions submitted a few were to be answered by Prof. Kroto himself. Therefore, I submitted two questions to Professor Kroto.
Two days ago, while searching for the answered questions, I found to my great surprise and happyness that both my questions have been answered, and I am transcripting his answers so as for you to have his answers also in text format. :)

Question 1



A: "Andrei Florea, two questions, question 12a:"
Q: "The mechanism for creating fullerenes is not yet fully understood. What would be the most likely explanation for that formation?"
A: "Well, it's pretty complicated, but it's quite clear that carbon is one of the fastest nucleating compounds, atoms or elements that we have and it zipps up to thousands very quickly from hot plasma and carbon molecules and graphites, these are down to actually melt, in fact no one seen liquid graphite to my knowledge, or liquid diamond... but I think what happens is from carbon atom plasma that we produce with a laser and we vaporize graphite, carbon chains first form, I think, liniar carbon, liniarish carbon C1, C2, C3, C4, C5, C6, so on; and my colleague David Walton really had a briliant way of making carbon chain molecules with just things on the end, so it was quite clear that you can make carbon chains of 30 or more carbon atoms. My guess is, what is happening in the range when they get to a 18, 19, 20, other things are forming and we think that there are also monocyclic rings forming in which the chain turns into a bead chain, you know... a ring carbon atoms in a monocyclic ring. I think that's now been proven by some really neat science by John Meyers Group in Basel and it was conjectured many years ago by theoreticians; then at around 20 to 30 to 40 to 50, I think these coalesce into cages and these cages may and we're pretty sure, we've got some results here a student pulled on working with myself and we showed that there are definitely spiecies with 28 carbon atoms which are cages, these circumstantial but nevertheless pretty definite cage structure. So at that point you've got your little baloons, if you wish. I think what happens then is carbon atoms and carbon molecules coalesce into this... ingested into this network of C40, C50 and so on and when they hit C60, they hit the first stable structure. C60 is the first stable fullerene. So a lot get locked into that, some get shooting on to C70 and others to higher ones. As you get these and you extract them, 10% of the soot, which are large particles, are in the form of fullerenes, sort of like, 80% to 90% C60, about 10% C70 and a few percent all the others with more and more carbon atoms and of course nanotubes and many other things. So, basically, I think that you have this cage forming at small levels and all others are being ingested into this structure and they stop when they get to C60 and that's why C60 is strong. And I think that's about as far as I'm prepared to go; it's just very, very complicated. Now people have been looking at the combustion process for 50 years, theorising and doing experiments. And they missed C60, so not sure they got it right, I don't know... it's very complicated and I think the best theory is my... theory; it all comes together. Best I can do."

Question 2



Q: "It has been proven that when chloroform is added to fullerenes, their structure changes from a cubic network of buckyballs to a hexagonal one, a process with impact on superconductivity. Why does this structural change occur?"
A: "Well, I don't know... I think the difference between hexagonal and cubic packing is a very, very low energy barrier, or a very small difference in barrier, so the impact of an intercalated molecule will be quite strong and the intermolecular forces will favour in the case of the chloroform structure, the hexagonal one."

In the end, I would like to thank Professor Harry Kroto and the nobelprize.org team for this incredible opportunity that I've been given and to invite you all to Ask a Nobel Laureate. :D