The near infrared spectra of the ionic complexes aniline(NH2)(+)-argon and aniline(ND2)(+)-argon have been measured by laser pho-, todissociation spectroscopy. The bands observed from 10500 to 13 500 cm(-1) have been assigned to the D-1((A) over tilde (2) A(2)) <- D-0 ((X) over tilde B-2(1)) transition within the solvated chromophore. They are characterized by a long vibrational progression involving the 6a mode. On the basis of CASSCF calculations, a large change of geometry along this coordinate is found while the amino group remains in the ring plane. Therefore, a change of the conjugation of the ring rather than a charge transfer is inferred. This is thought to be the origin of the extent of the progression. (c) 2005 Elsevier B.V. All rights reserved.