Hidden role of intermolecular proton transfer in the anomalously diffuse vibrational spectrum of a trapped hydronium ion.

ABSTRACT: We report the vibrational spectra of the hydronium and methyl-ammonium ions captured in the C_3v binding pocket of the 18-crown-6 ether ionophore. Although the NH stretching bands of the CH₃NH₃⁺ ion are consistent with harmonic expectations, the OH stretching bands of H₃O⁺ are surprisingly broad, appearing as a diffuse background absorption with little intensity modulation over 800 cm^-1 with an onset ∼400 cm^-1 below the harmonic prediction. This structure persists even when only a single OH group is present in the HD₂O⁺ isotopologue, while the OD stretching region displays a regular progression involving a soft mode at about 85 cm^-1 These results are rationalized i

SUBMITTER: Craig SM 

PROVIDER: S-EPMC5474800 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature