title: Hydration properties of small hydrophobic molecules by Brillouin light scattering.
abstract: We study the relaxation of water molecules next to hydrophobic solutes with different functional groups by Brillouin light scattering. Evidence is given for (i) water activation energy in trimethylamine-N-oxide, proline and t-butyl alcohol diluted solutions which is comparable to that of neat water, almost independent from solute mole fraction and (ii) moderate slowdown of relaxation time of proximal water compared to the bulk, which is consistent with excluded volume models. Assuming that the main contribution to viscosity comes from bulk and hydration water, a rationale is given of the phenomenological Arrhenius' laws for the viscosity of diluted aqueous solutions.
authors.affiliation: IOM-CNR, c/o Dipartimento di Fisica, Università di Perugia, I-06123, Perugia, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Comez
authors.forename: L
authors.initials: L
authors.lastname: Lupi
authors.forename: M
authors.initials: M
authors.lastname: Paolantoni
authors.forename: F
authors.initials: F
authors.lastname: Picchiò
authors.forename: D
authors.initials: D
authors.lastname: Fioretto
mesh_terms: D057927:Hydrophobic and Hydrophilic Interactions; D008027:Light; D008744:Methylamines / Q000737:chemistry*; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D011392:Proline / Q000737:chemistry*; D012542:Scattering, Radiation; D012996:Solutions; D014783:Viscosity; D014867:Water / Q000737:chemistry; D020002:tert-Butyl Alcohol / Q000737:chemistry*
chemical_list: D008744:Methylamines; D012996:Solutions; D014867:Water; D011392:Proline; C005855:trimethyloxamine; D020002:tert-Butyl Alcohol