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Stereographic photograph (1903) of the captured Man-eater of Calcutta in the Calcutta zoo. The tiger had earlier claimed 200 human victims.

#Asktheauthor: How carbon atoms cross energy barriers (and tigers don't)

Angew. Chem.: 3 Questions to RESOLV scientist Wolfram Sander about his recent Angewandte Chemie publication on heavy atom tunneling.

1. What is the new discovery that you made?

In our experiments we found that the molecule Monodeuterated 1,5-dimethyl-semi-bullvalene undergoes rearrangement from a less stable to a more stable configuration at temperatures as low as 3 K (-271 oC) despite an activation barrier of 4.8 kcal/mol. We ascribe these results to carbon atom tunneling, a very rare quantum mechanical effect. Our experiments confirm an earlier theoretical prediction for this beaviour of the dimethylsemibullvalene. 

2. What is its significance? 

We found another example (of the few out there) that carbon atoms can behave like waves, not only like particles. Therefore, they can overcome an energetic barrier even if they don’t have enough energy to cross that barrier - this is called tunneling. Imagine a tiger leaving a cage without jumping over the fence, since the fence is too high for it. Fortunately, the tunneling probability depends strongly on the mass of the tunneling particle, and the probability for a tiger to tunnel is negligibly small (although not zero). This is well known to happen for electrons and hydrogen atoms, but it has been rarely proven for relatively heavy atoms like carbon.

The phenomenon of tunneling is of fundamental importance in physics and chemistry. For example electron tunneling is the basis for a very important imaging technology like the Scanning Tunneling Microscope (STM). And hydrogen tunneling contributes to numerous reactions in chemistry and biology.  

3. Is this related to Solvation Science?

Yes. Tunneling is very much influenced by solvents, but it is totally unknown how.

Link to RUB press release

Link to original publication

Leading actor: the solvent

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