2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/87619The role of symmetry adaptation techniques in multi-photon spectroscopy of partly-filled shell ions in crystals is briefly reviewed. This leads to an intensity formula which is discussed from a qualitative point of view.11 pages, Tex fileAtomic and Molecular ClustersSoft Condensed MatterChemical PhysicsMulti-Photon Laser Spectroscopy of Transition Ions in Crystals: Recent Progress in the Use of Symmetry Considerationstext