Surface adsorption: Quantum reflection versus polaron collapse

We present a quantum theory for surface adsorption of low-energy charged particles on a dielectric fluid. Quantum effects suppress adsorption (quantum reflection), while polaronic-mass enhancement and coherence loss for the wave function assist it. We provide additional evidence that the sticking coefficient has a singular dependence on the coupling constant which enters the particle-substrate excitation interaction. The system exhibits a transition from perturbative quantum-mechanical regime to a strong-coupling classical regime. We use a time-dependent generalization of the Lee-Low-Pines variational wave function to study the critical regime of intermediate-coupling constants where the transition takes place. The onset of classical adsorption is found to be triggered by the appearance of collapsed bound states on the substrate surface.