Silver-carbon clusters were formed by dual Nd:YAG laser vaporization, trapped in a solid Ar matrix at 12 K, and investigated by infrared spectroscopy. Two new infrared absorption bands were observed at 1827.8 and 1231.6 cm(-1). Isotopic ((13)C) substitution experiments were performed to aid in their assignment. Possible structures considered for the carrier of these bands were Ag(m)C(n) with m = 1 and 2 and n = 1-3, all of which were investigated by density functional theory calculations. The geometries and associated vibrational harmonic-mode frequencies of these clusters were computed with the MPW1PW91 functional and SDD basis set. Both calculations and (13)C-isotopic substitution experiments indicate that the new bands are due to the asymmetric and symmetric C=C stretching modes, respectively, in near-linear AgC3.