We report on the absorption, resonance Raman, and Raman excitation profile spectra of mass-selected gadolinium dimers in argon matrices. Two dimer absorption bands were found between 570 and 660 nm. The Raman excitation profile resembles the dimer absorption spectrum very well. Resonance Raman spectra, obtained by excitation into this region with dye laser radiation, give a single progression with up to four Stokes transitions. These data give omega(e)=138.7 +/- 0.4 cm(-1) with omega(e)x(e)=0.3 +/- 0.1 cm(-1), leading to a spectroscopic dissociation energy of 2.1 +/- 0.7 eV.