The Raman scattering spectra of M 0(1) centers ( M=Ga, In, and Tl) in KCl, which possess the laser-active type structure, have been resonantly excited in their optical transitions (OT3). The low frequency resonances at 59, 45, and 30cm -1, respectively, are attributed to the totally symmetric motion of the impurity atom along the fourfold axis in the C 4 v point group of the defects. The spectral distribution of the defect-induced first order phonon spectrum is remarkably similar for the three centers, showing that it essentially reflects the motion of the surrounding ions. The differences with an F-center-like phonon spectrum, in particular, the high relative intensity of the low frequency resonances indicate a dominant coupling of the electron with the motion of the heavy metal impurity and therefore illustrate the predominantly atomic character of these defects. The Raman spectrum of In 0(1) in NaCl almost exclusively consists of the fundamental vibration of In 0 and its overtones. A correspondence is indicated between this discrete character of the Raman spectrum and the electronic properties of the M 0(1) defects in the NaCl host lattice.