Chemisorption-Induced Activation of MgCl2 Film as Realistic Route for Heterogeneous Ziegler–Natta Surfaces under Ultrahigh Vacuum

The preparation of model Ziegler–Natta (ZN) surfaces under ultrahigh vacuum necessitates the activation of MgCl2 films deposited on a substrate, since these films unexceptionally expose the energetically most stable but catalytically inactive (001) face. Here, we present a method to activate MgCl2 films with the inactive (001) termination, which was based on the chemisorption of a Lewis base in an analogous way to industrial powder catalyst preparation. We found that a (001)-terminated MgCl2 film on Cu(110) was activated into a MgCl2·Lewis base adduct when exposed to a pyridine vapor at a nearly saturated vapor pressure. A dynamic response of the MgCl2 film to the chemisorption and desorption of a Lewis base was uncovered using low-energy electron diffraction and temperature-programmed desorption.