Dynamical quantum filtering in hydrogen–surface reactions

Abstract

We report on how surfaces that adsorb hydrogen could act as rotational quantum state filters and cause, for example, D 2 molecules desorbing in the vibrational ground state from Cu(111) to exhibit strong rotational alignment. For low final translational energies, we found that desorbing D 2 molecules have rotational alignment factor values corresponding to cartwheel-type rotational preference. As the final translational energy increases, the corresponding alignment factor increases initially to values corresponding to helicopter-type rotational preference and then, eventually, decreases to values almost compatible with a spatially isotropic distribution, as the translational energy increases further.