Electron Spin Resonance Investigations of the Molecular Motion of N${\mathrm{O}}_2$ on ${\mathrm{Al}}_2$${\mathrm{O}}_3$(111) under Ultrahigh Vacuum Conditions

We report on the first observation of electron spin resonance spectra of submonolayer coverages of small adsorbates on an epitaxially grown single crystal ${\mathrm{Al}}_2$ ${\mathrm{O}}_3$ film under ultrahigh vacuum conditions. The spectra reveal a clear temperature and coverage dependence. The changes of linewidths and intensities as a function of surface temperature and coverage provide insight into diffusion processes on the ${\mathrm{Al}}_2$ ${\mathrm{O}}_3$ surface.