Time-resolved EPR (TREPR), transient absorption, and phosphorescence spectra have been measured in solid matrixes at 77 K for the covalently linked L-shaped dimers of naphthalene, in which the in-plane long axes of the two naphthalene moieties are parallel and the in-plane short axes make an angle. The zero-field splitting (ZFS) parameters obtained by simulation of the TREPR spectra are consistent with the dimer geometries, if it is assumed that excitation exchange interaction is responsible for the small D values of the dimers relative to the monomer. The tilt angle in the triplet state is significantly smaller for the dimers exhibiting excimeric phosphorescence than those exhibiting monomeric emission. Comparison of the spectral position and Lifetime of phosphorescence from the L-shaped dimers with those from the sandwich dimers indicates that the excitation exchange interaction is substantially greater for the L-shaped dimers as compared to the sandwich dimers. The proposal that the preferred conformation of the triplet excimer of naphthalene is L-shaped, rather than sandwich, is supported by the measurements.