The direction of propagation of acoustic phonons emitted by electron relaxation in weakly confined, parabolic quantum dots charged with one or two electrons is studied theoretically. The emission angle strongly depends on the energy of the phonon, the dominant electron-phonon scattering mechanism ͑deformation potential or piezoelectric field͒, and the orbital symmetries of the initial and final electron states. This leads to different behaviors for phonons emitted by electrons relaxing between

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... evels of single and coupled quantum dots. Our results establish the basis to control the direction of propagation of phonon modes triggered by transitions in quantum dot systems.