Details

Autor(en) / Beteiligte

• Horsewill, Anthony J.
• Jones, Nicholas H.
• Caciuffo, Roberto

Titel

Evidence for Coherent Proton Tunneling in a Hydrogen Bond Network

Ist Teil von

• Science (American Association for the Advancement of Science), 2001-01, Vol.291 (5501), p.100-103

Ort / Verlag

Washington, DC: American Society for the Advancement of Science

Erscheinungsjahr

2001

Quelle

Science Online科学在线

Beschreibungen/Notizen

• We observed coherent proton tunneling in the cyclic network of four hydrogen bonds in calix[4]arene. The tunneling frequency of 35 megahertz was revealed by a peak in the magnetic field dependence of the proton spin-lattice relaxation rate measured with field-cycling nuclear magnetic resonance in the solid state at temperatures below 80 kelvin. The amplitude of the coherent tunneling peak grows with temperature according to a Boltzmann law with energy D/kB= (125 ± 10) kelvin (where kBis Boltzmann's constant). The tunneling peak can be interpreted in the context of level crossings in the region where the tunneling frequency matches the proton Larmor frequency. The tunneling spectrum reveals fine structure that we attribute to coupling between the hydrogen bonds in the network. The characteristics of the tunneling peak are interpreted in the context of the potential energy surface experienced by the hydrogen atoms in the network.