Effect of pressure on hydrogen bonding in liquid methanol

We have investigated the effect of pressure on the hydrogen bonding in liquid methanol using Raman spectroscopy. Specifically, we have measured the OH and CO stretching modes and assigned the bands, in agreement with recent IR and crossed molecular beam experiments on methanol clusters. At about 7 to 8 kbar, we note indications that the intrinsic nature of the methanol clusters in our samples has changed. Our results provide support for and extend conclusions derived from Monte Carlo simulations, explain anomalies observed by previous researchers, and provide new insights into general hydrogen-bonding phenomena.