The FTIR spectra of Ar(Ne)/CF4 matrixes have been recorded at matrix concentrations varying in the range 10 000-600 cm-1. The absorptions due to the CF4 monomers and to the (CF4)2 resonance dimers in the spectra of the two matrixes have been identified. The intramolecular Fermi resonance in the spectra of the CF4 monomers trapped in solid argon and neon has been analyzed. The spectra of the (CF4)2 dimers are determined by the strong resonance dipole-dipole interaction of the two interacting molecules and by strengthening or weakening of the intramolecular Fermi resonance interaction. © 2006 Elsevier Inc. All rights reserved.