The photodissociation dynamics of bare I-2(-) and I-2(-). Ar at 413 and 390 nm have been investigated using a fast beam instrument coupled with a new photofragment coincidence imaging detector. Results from the application of this technique to the dissociation of I-2(-) and I-2(-). Ar yielded the dissociation energy of I-2(-) (D-0(I-2(-)) = 1.012 +/-0.008 eV) and I-2(-)-Ar binding energy (D-0(I-2(-)-Ar) = 45 +/- 8 meV). The experiments show that at these wavelengths, I-2(-). Ar undergoes three-body dissociation to I- + I* + Ar, with very low momentum in the Ar atom and unequal momentum partitioning between the two I atoms. (C) 2003 Elsevier Science B.V. All rights reserved.