  Topological effects in edge states are clearly visible on short lengths only,
thus largely impeding their studies. On larger distances, one may be able to
dynamically enhance topological signatures by exploiting the high mobility of
edge states with respect to bulk carriers. Our work on microwave spectroscopy
highlights the responses of the edges which host very mobile carriers, while
bulk carriers are drastically slowed down in the gap. Though the edges are
denser than expected, we establish that charge relaxation occurs on short
timescales, and suggests that edge states can be addressed selectively on
timescales over which bulk carriers are frozen.
