We report the infrared (IR) absorption spectrum of the jet-cooled neutral a
niline-Ar Van der Waals complex together with that of the aniline-Ar cation
in the 350-1700 cm(-1) range. The spectra are measured using mass-selectiv
e ion detection in two different IR-ultraviolet double-resonance excitation
schemes, using a free-electron laser as a source of widely tunable, intens
e IR radiation. A comparison with calculated IR spectra of the bare neutral
aniline and of the cation of aniline allows for an unambiguous assignment
of all the observed modes. The dissociation limit of the neutral aniline-Ar
complex is bracketed between 273 and 329 cm(-1), significantly lower than
previously estimated. (C) 1999 American Institute of Physics. [S0021-9606(9
9)02504-0].