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In popularizations, people tunnel through walls or doors. But what can really tunnel through a graphene sheet without tearing it?

According to Wikipedia, a single layer of graphene absorbs 2.3 % of white light, but 97% makes it through. It conducts electrons well enough to make a transistor.

I doubt that a baseball tunnels through a sheet of graphene without harming it.
But what about a Buckyball? or a smaller molecule? A helium atom? A bare proton?

This looks deceptively like the one dimensional finite barrier problem in elementary QM textbooks. Can we calculate the probability of a given projectile at a given velocity tunnelling through the graphene sheet? Is there any experimental data?

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Bloody Helium atoms get through all kinds of stuff, a fact which is a constant pain in the neck for particle experimenters. Especially as helium can have adverse effects on PMTs (see the "Handling precautions section of jp.hamamatsu.com/products/sensor-etd/pd002/pd395/index_en.html for instance). –  dmckee Apr 28 '12 at 2:52
    
Yes, I knew that. But I don't know if or how fast they go through graphene. Also is that tunnelling or is it diffusion? Is there a difference? –  Jim Graber Apr 29 '12 at 14:55
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up vote 2 down vote accepted

(sorry I have to split this up because StackExchange won't let me post more than two links)

Even helium atoms (at reasonable temperatures) do not tunnel through graphene, as the potential energy barrier is far too high. (source: Leenaerts et al. 2008)

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However, suitably small holes may allow for tunneling of helium atoms through graphene-like materials at room temperature and below (source: Schrier 2010, Hauser and Schwerdtfeger 2012)

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(sorry I have to split this up because StackExchange won't let me post more than two links)

For protons, the barrier height is much lower, so tunneling can be appreciable. (source: Miao et al. 2013 )

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