Hopping of the photohole during photoemission from physisorbedN2: The influence of band formation on vibrational excitation

${\mathrm{N}}_2$ physisorbed on top of a Xe spacer layer on Ag(111) and Pd(111) has been studied by angle-resolved and polarization-dependent UV photoemission. The ${\mathrm{N}}_2$ 1${\mathrm{\pi }}_{\mathit{u}}$ valence level exhibits a vibrational fine structure due to two multiplets corresponding to the ionic (${\mathrm{N}}_2^{+}$) and neutral (${\mathrm{N}}_2$) states. The neutral-state multiplet is explained through hopping of the photohole during photoemission. We show that its intensity is stronger for emission from the in-plane component of 1${\mathrm{\pi }}_{\mathit{u}}$, than for the perpendicular one. This is due to a larger lateral overlap in the former case, as concluded by the observed band formation.