  Antiferromagnetic spin-1 chains host the celebrated symmetry protected
topological Haldane phase, whose spin-1/2 edge states were evidenced in bulk
by, e.g., Electron Spin Resonance (ESR). Recent success in assembling effective
spin-1 antiferromagnetic chains from nanographene and porphyrin molecules opens
the possibility of local, site-by-site, characterization. The nascent technique
of combined ESR-STM is able to measure the spin dynamics with atomic real-space
resolution, and could fully reveal and manipulate the spin-1/2 degree of
freedom. In this work, we combine exact diagonalization and DMRG to investigate
the local dynamic spin structure factor of the different phases of the
bilinear-biquadratic Hamiltonian with single-ion anisotropy in presence of an
external magnetic field. We find that the signature of the Haldane phase is a
low-energy peak created by singlet-triplet transitions in the edge-state
manifold. We predict that the signature peak is experimentally observable,
although for chains of length above N = 30 its energy should be first tuned by
application of external magnetic field. We fully characterize the peak in
real-space and energy, and further show its robustness to weak anisotropy and a
relevant range of temperatures.
