Structure Making and Breaking Effects of Cations in Aqueous Solution: Nitrous Oxide Pump-Probe Measurements.

摘要: Ultrafast IR pump-probe responses resonant with the ν3 asymmetric stretch of nitrous oxide (N2O) at ∼2230 cm-1 are reported for 2 M aqueous salt solutions MgCl2, CaCl2, NaCl, KCl, and CsCl room temperature. The solvated cations these chloride span range from strongly to weakly hydrating ions, correspondingly often categorized as structure makers breakers, respectively. observed dependent trends N2O vibrational energy relaxation (VER) rotational reorientation anisotropy (R(t)) decays consistent categorization breakers or makers, show evidence effects on water hydrogen bonding network beyond first solvation shell ions. This mode is H2O bend-libration band region. corresponding FTIR fitted well by a two Gaussian plus sloping continuum baseline model that allows framework characterizing perturbations solvent spectral density in Both coupling strengths states appear contribute systematic cation T1 here. R(t) follow bulk viscosity values. These results contrasted previous studies predominantly based dynamics OH/OD HOD bonded anions solutions.