Chemisorption characteristics of methylnitrene diradicals adsorbed on Cu(1 1 0) studied by UPS and PEEM

Clean adsorption of CH3N radicals on Cu(1 1 0) is achieved by thermal decomposition of azomethane molecules at 300 K. UV-photoemission spectra at various surface coverages are obtained and assigned to appropriate molecular orbitals. From UPS, the change in surface work function due to the radical adsorption is also determined. This change is utilized for imaging the spatial distribution of the adspecies by photoemission electron microscopy. It is found that at low coverages, the radicals tend to aggregate into small two-dimensional islands on the Cu surface. Such chemisorption behavior can be correlated with the first-order reaction kinetics observed in thermal desorption