2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/211544We clarify the purely imaginary quasinormal frequencies of a massless scalar perturbation on the 3D charged-dilaton black holes. This case is quite interesting because the potential-step appears outside the event horizon similar to the case of the electromagnetic perturbations on the large Schwarzschild-AdS black holes. It turns out that the potential-step type provides the purely imaginary quasinormal frequencies, while the potential-barrier type gives the complex quasinormal modes.19 pages, 8 figuresGeneral Relativity and Quantum Cosmologytext