Interface formation of pentacene on $Al2O3$ Available to Purchase

We examined the interface formed by pentacene deposition onto an $Al2O3$ substrate. We found that upon pentacene deposition onto $Al2O3$ the pentacene vacuum level aligns with that of $Al2O3.$ We observe the immediate appearance of a measurable pentacene molecular orbital near the Fermi level upon deposition of as little as 2 Å of pentacene onto the $Al2O3$ surface. This suggests that there are no chemical bonds at this interface. The vacuum level change at the interface dipole is found to be less than 0.25 eV, and at least part of it can be attributed to the oxygen adsorbates at the in situ prepared aluminum oxide surface.