Coherent tunnel repolarization of a short hydrogen-bonded chain

We suggest a possible mechanism of polarization oscillations of a short hyd rogen bonded chain, which is due to coherent proton tunneling along hydroge n bonds and/or around heavy atoms. Such oscillations are similar to the eff ect of coherent spin tunneling which was observed in small magnetic grains and mesoscopic magnetic molecules. With the aid of the WKB approximation th e tunneling frequency of these transitions is calculated. The tunneling rat e of such flip-flop process does not depend on temperature, and the effect of coherent chain repolarization can be observed at low temperatures when t unneling processes prevail over thermal activation ones. (C) 1999 Elsevier Science B.V. All rights reserved.