▎ 摘　　要

Micro-magneto-Raman scattering spectroscopy is made use of to probe magneto-phonon resonances (MPR) in suspended mono- to pentalayer graphene. MPR correspond to avoided crossings between zone-center optical phonons (G-mode) and optically active inter-Landau level (LL) transitions and provide a tool to perform LL spectroscopy at a fixed energy (approximate to 197 meV) set by the G-mode phonon. Using a single-particle effective bilayer model, the velocity parameter associated with each MPR is readily extracted. A single velocity parameter slightly above the bulk graphite value suffices to fit all MPR forN >= 2 layer systems. In contrast, in monolayer graphene, it is found that the velocity parameter increases significantly from (1.23 +/- 0.01) x 10(6) m s(-1)up to (1.45 +/- 0.02) x 10(6) m s(-1)as the first to third optically active inter-LL transitions couple to the G-mode phonon. This result is understood as a signature of enhanced many-body effects in unscreened graphene.