The charge distribution and binding features of aniline/benzene hetero-trimer and aniline homo-trimer ions are investigated by vibrational spectroscopy and by near-infrared photodissociation and spontaneous unimolecular dissociation of mass-selected cluster ions. The absence of the charge resonance absorption indicates the charge localization in the trimer ions. Substantial red-shifts and enhanced intensities of the vibrational transitions suggest strong perturbations to the NH oscillators. The trimer ions are stabilized by the hydrogen-bonding interaction through the NH2 group of the charged aniline with the neutral molecules rather than the charge-delocalization interaction among the component molecules.

This work was supported in part by the Joint Studies Program (2001) of the Institute for Molecular Science and the Grant-in-Aid for Scientific Research (No. 11440177) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

This is a postprint of an article published by Elsevier B.V. in Chemical Physics Letters, 2002, available online: http://doi.org/10.1016/S0009-2614(02)00490-6