ROTATIONAL ISOMERIZATION IN A CHEMISORBED LAYER - ETHYL FORMATE ON NI(111)

Reflectance absorbance infrared spectroscopy (RAIRS) and thermal desor ption data for ethyl formate on Ni(111) display a surface coverage dep endence consistent with rotational isomerization within the chemisorbe d layer. The (Z)-gauche adsorbate conformation is selectively populate d at low surface coverages, and conversion to the (E)-trans conformati on occurs as the surface coverage is increased. This interconversion s ets in at coverages where lateral interactions within the adsorbed lay er become evident, thereby suggesting an important role for steric eff ects.