Knowledge Bank

In protonated binary clusters, location and magnitude of delocalization of the excess proton is shown to correlate to the difference of the proton affinities of the two components\textbf{316}, 249 (2007).}. Theoretical calculations on a series of protonated binary clusters have shown that Fermi resonance can occur in clusters containing amines. For examples, in (CH$3$)$3$N-H$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$-X, the N-H$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ stretching frequency is high than the first overtone of N-H$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ bending modes. As the N-H$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ stretching frequency decreases by increasing the proton affinity of X, Fermi resonance inevitably shall occur. At least both N-H$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ bending modes seem to couple with the N-H$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ stretching mode; we performed multi-dimensional mode analyses to understand this coupling.