Hydrogen-bonded phenol-acid clusters studied by vibrational resolved laserspectroscopy and ab initio calculations - II. Acetic acid

Phenol(CH3COOH)(n) clusters are studied by laser spectroscopy up to n=4 and by ab initio calculations on the Hartree-Fock/6-31G(d,p) level up to n = 2 . The resonant two-photon ionization (R2PI) spectra do not show any intense signal belonging to phenol(CH3COOH)(1) in contrast to the corresponding cl uster with formic acid. IR-W double-resonance and dispersed fluorescence sp ectra point to a geometry of the n = 2 (3) cluster where the phenol molecul e acts as proton donor bound to the acetic acid dimer (trimer). Other isome rs like a cyclic arrangement as in phenol(HCOOH)(2) are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.