Proton Transfer Assisted by a Low-frequency Mode Excitation

Proton Transfer Assisted by a Low-frequency Mode Excitation 

Due to the relatively small mass of the proton it is assumed that tunneling effects play a crucial role in many proton and hydrogen atom reactions, and that they determine many specific properties of H-bonded systems in the gas and condensed phases [38], It should be noted, however, that proton tunneling has been proved experimentally for only a relatively small number of H-bonded systems in the gas phase and in crystals. 

In solids there are many low-frequency modes which can influence the proton movement and thus affect its magnetic relaxation. Only the stretching and rocking intracomplex vibration modes seem to be sufficiently strongly coupled with the proton coordinate to account for relaxation. The 0- -0 stretching vibration was used in Refs. [35, 56] as the low-frequency (promoting) mode. 

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