  We study excitations and collisions of kinks in a scalar field theory where
the potential has two minima with $Z_2$ symmetry. The field potential is
designed to create a square well potential in the stability equation of the
kink excitations. The stability equation is analogous to the Schr\"{o}dinger
equation, and therefore we use quantum mechanics techniques to study the
system. We modify the square well potential continuously, which allows the
excitation to tunnel and consequently turns the normal modes of the kink into
quasinormal modes. We study the effect of this transition, leading to energy
leak, on isolated kink excitations. Finally, we investigate kink-antikink
collisions and the resulting scaling and fractal structure of the resonance
windows considering both normal and quasinormal modes and compare the results.
