Article ID: 2025-036
In the repulsive desorption of hyperthermal products, rotation and translation are simultaneously excited by a common repulsion, resulting in mode coupling (MC). This review highlights the MC in repulsive desorption since it plays a key role in both the energy partitioning (EP) of the products to each mode and the structural sensitivity of desorption dynamics. It has long been overlooked due to non-angle-resolved (AR) energy analysis that ignores the desorption-angle dependence of the rotational and translational energies. The non-AR flux or energy analysis has prevented the desorption dynamics from being structure-sensitive since the structural information of desorption sites (symmetry, slope, and transition state orientation) can be extracted from the anisotropy of the product flux and energy distributions. Typical examples of the EP due to MC between translation and rotation include the combinative D2 desorption on Cu(111), and the N2 desorption from the decomposition of adsorbed N2O on Pd(110)(1×1). For the former, the released energy is largely conserved in desorbed D2 and the anti-correlation between the rotational and translational energies is clear. For the latter, the anti-correlation is weak due to the intense energy dissipation before desorption. An explanation is given for the misuse of the detailed balance principle in non-equilibrium desorption.
