The electronic spectroscopy of jet-cooled 1,2 ' -binaphthyl has been examined by laser-induced fluorescence spectroscopy. Many medium length progressions were observed in two active vibrations with frequencies nu (A ') = 35.1 cm(-1) and nu (B)' = 53.5 cm(-1) assigned as the torsion and out-of-plane wag between the two naphthalene moieties, respectively. Two other low-frequency vibrations were measured: nu (C)' = 60.6 cm(-1) and nu (D)' = 138.1 cm(-1). These are also likely to involve inter-ring motion, possibly an in-plane wag for ve and an antisymmetric inter-ring motion for nu (D), although a low-frequency naphthalene ring vibration is also possible. The electronic origin transition was not observed because of a very weak Franck-Condon factor with the ground state. However, a Franck-Condon analysis provided an estimate of the origin transition at T-00 = 30 828.2 cm(-1) Progressions in both nu (A) and nu (B) are harmonic up to 13 quanta for nu (A) and 5 quanta for nu (B). Therefore, the barrier for interconversion between the cis and trans conformers of 1,2 ' -binaphthyl must be much higher than the 500 cm(-1) of harmonic vibrations measured here. A diffuse band, about 800 cm(-1) higher in energy, was assigned to the S-2 <-- S-0 transition. Previous semiempirical calculations predicted the electronic energy of the SI state and the magnitude of the naphthalene dimer splitting quite well. However, the calculations placed the interconversion barrier through 90 degrees to be as low as 300 cm(-1). The Franck-Condon analysis also provided a change in equilibrium conformation angle of 18 degrees upon electronic excitation, again in disagreement with calculations, which predict essentially no change in equilibrium torsional angle between the S-0, S-1, and S-2 states.