"The O-H stretching Raman band of HOD in D2O is simpler than the spectrum of H2O because, (i) due to mass difference the vibrations of the OD and OH bands of the same molecule are decoupled (intramolecular decoupling), and (ii) due to isolation of O-H oscillators, the interaction between the stretching vibration of a given molecule and the vibration of its neighboring molecules is decoupled (intermolecular decoupling). Thus the O H stretching Raman band of the isolated O-H oscillator reflects the local environment of O-H oscillators. The fact that even the decoupled O-H stretching vibration gives rise to a broad and asymmetric band indicates that the electromagnetic field around the individual O-H oscillator, which is mainly determined by hydrogen bond strengths, has a broad distribution" .