Hydrogen bonds at low temperatures: new data from subpicosecond hole burning spectroscopy

This study presents data of 2,2-dimethyl-3-ethyl-3-pentanol (DMEP) for the first time measured at low temperatures down to 15 K with a two color IR sub-picosecond pump-probe hole burning experiment. In addition, the investigation recorded temperature dependent conventional FT-IR spectra. The results substantiate the role of those combination modes for the broadening of the OH absorption band even in the simple case of a dimer bond. The relaxation dynamics of the OH stretching vibration is shown to accelerate at low temperatures, accompanied by a strengthening of the hydrogen bonds. In particular, the average T₁ lifetime of the OH-stretch decreases from 4 ps at room temperature to 2.5 ps at 15 K.