Quantum-size effects in thin solid xenon films

We have measured decay spectra following the N 1s-PI* transition in N2 with vibrational resolution in both the intermediate and final states. Using photon energy steps of 60 meV subtle changes in both the participator and spectator lines were observed. In particular, spectra measured at photon energies on the low-energy side of the first vibrational component of the absorption curve ("detuning") gave rise to vibrational collapse of the participator lines. At higher photon energies vibrational-lifetime interference is observed on both participator and spectator lines.