We report on the control of wave packet dynamics for the ionization of K-2 attached to the surface of superfluid helium droplets. The superfluid helium matrix acts as a heat sink and reduces the coherence time of molecular processes by dissipation. We use tailor-shaped pulses in order to activate or inhibit different ionization paths by constructive or destructive wave packet interference. A drastic change of the wave packet dynamics is observed by shifting the phase between the exciting sub pulses. (C) 2016 Elsevier B.V. All rights reserved.