Double tunneling: An overlooked quantum effect in anionic molecular clusters
Simultaneous tunneling of an electron and nuclei in hydrogen-bonded molecular clusters which support a dipole bound electron is reported. A whole class of systems including hydrogen halide and water dimer anions is predicted to exhibit this effect. A measurable signature of double tunneling is a strong reduction of the tunneling splitting compared to the neutral cluster. Quantum mechanical calculations give for the hydrogen fluoride dimer anion a ground-state tunneling splitting of 114 MHz, while for the first excited vibrational state the tunneling splitting reaches 4.20 GHz.
Jungwirth
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J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague 8, Czech Republic.
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