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 570-660 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 w_e = 138.7 ± 0.4 cm-1 with w_ex_e = 0.3 ± 0.1 cm-1, leading to a spectroscopic dissociation energy of 2.1 ± 0.7 eV.