Hydrophobic molecules slow down the hydrogen-bond dynamics of water.

摘要: We study the spectral and orientational dynamics of HDO molecules in solutions tertiary-butyl-alcohol (TBA), trimethyl-amine-oxide (TMAO), tetramethylurea (TMU) isotopically diluted water (HDO:D2O HDO:H2O). The are studied with femtosecond two-dimensional infrared spectroscopy polarization-resolved vibrational pump−probe spectroscopy. observe a strong slowing down diffusion around central part absorption line that increases increasing solute concentration. At low concentrations, fraction showing slow is observed to scale number methyl groups, indicating this effect due hydrogen-bond hydration shell groups molecules. frequency strongly correlated mobility This correlation indicat...