Control of the shape of chemical wave patterns in the NO + H₂ reaction on Rh(110) by adsorbate-induced reconstructions

The NO + H2 reaction on Rh(110) has been investigated between 480 and 650 K under isothermal low-pressure conditions at 10−6 and 10−5 mbar. Photoemission electron microscopy (PEEM) was used as a spatially resolving method. Depending on the experimental parameters, a variety of different chemical wave patterns such as elliptically and rectangularly shaped target patterns or travelling wave fragments were found. The existence range of these patterns has been mapped out in the pH2, T-parameter range for fixed pNO=1.6×10−6 mbar. In low energy electron diffraction (LEED) a number of different nitrogen and oxygen induced reconstructions was observed in the pattern-forming parameter range. The variations in the shape of the wave patterns were traced to the presence of adsorbate-induced reconstructions with different anisotropy caused by atomic oxygen and atomic nitrogen, respectively