Electron tunneling or flickering resonance?

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Science  01 Aug 2014:
Vol. 345, Issue 6196, pp. 527-528
DOI: 10.1126/science.345.6196.527-e

When electrons move from one site to another in biological molecules and the transfer drops off exponentially with distance, physicists usually assume they're seeing the electrons quantum-tunneling through energy barriers. A theoretical study by Zhang et al. provides a different interpretation. Molecules with the right combination of sites, with energy levels that align fleetingly during structural fluctuations, can produce the same decay signature. These “flickering resonances” temporarily create a band-like state for the electron, and as more sites are involved (corresponding to longer distances), the probability of creating the resonance drops exponentially. This mechanism operates over scale lengths of up to about 15 angstroms and could explain the short-distance electron transfer between bases in DNA.

Proc. Natl. Acad. Sci. U.S.A. 10.1073 pnas.1316519111 (2014).

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