Characterization of the hydrogen-bonded cluster ions [phenol-(H2O)n]+ (n=1-4), (phenol)2+, and (phenol-methanol)+ as studied by trapped ion infrared multiphoton dissociation spectroscopy of their OH stretching vibrations
T. Sawamura, A. Fujii, S. Sato, T. Ebata, and N. Mikami,
J. Phys. Chem. 100, 8131 (1996).

OH stretching vibrations of hydrogen-bonded cluster ions of phenol (PhOH), [PhOH-(H2O)n]+ (n=1 - 4), (PhOH)2+, and (PhOH-methanol)+ have been observed with infrared photodissociation spectroscopy in combination with an ion-trapping technique. Cluster ions were efficiently generated by ionization of phenol followed by a jet expansion and were mass-selectively stored by the radio frequency ion trap method, which allows us to observe infrared multiphoton dissociation yield spectra of size-selected cluster ions. For [PhOH-(H2O)n]+, the OH stretching vibrations of the water moieties strongly suggested that the n3 cluster ions exhibit the proton-transferred form, [PhO-H3O+(H2O)n-1], while the n=1 and 2 ions are of the nontransferred form, [PhOH+-(H2O)n]. As for (PhOH)2+, the infrared spectra indicate that the dimer ion is characterized as the open form, in which the phenol ions acts as a proton donor and the neutral phenol as an acceptor through their single hydrogen bond. The similar open form is also found for (PhOH-methanol)+, in which the phenol ion acts as a proton donor.

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