  We analyze high-resolution scanning tunneling spectra of the electron-doped
cuprate Pr0.88LaCe0.12CuO4 (T_c = 24 K). We find that the spectral fine
structure below 35 meV is consistent with strong coupling to a bosonic mode at
16 meV, in quantitative agreement with early tunneling spectra of
Nd1.85Ce0.15CuO4. Since the energy of the bosonic mode is significantly higher
than that (9.5-11 meV) of the magnetic resonance-like mode observed by
inelastic neutron scattering, the coupling feature at 16 meV cannot arise from
strong coupling to the magnetic mode. The present work thus demonstrates that
the magnetic resonance-like mode cannot be the origin of high-temperature
superconductivity in electron-doped cuprates.
