Isonicotinic Acid Molecular Films on Ag(111): I. XPS and STM Studies of Orientational Domains

Abstract

Molecular self-assembly of isonicotinic acid (INA) on Ag(111) was studied using STM and XPS. INA molecules organize into an ordered layer structure commensurate with the Ag(111) surface. A head-to-tail hydrogen-bond configuration was determined for the self-assembled structure based on STM observations and corroborated by XPS core-level shifts. The monolayer structure is closely related to the (100) surface of the INA crystalline solid. Monolayer domains, commensurate with the Ag(111) substrate, are sorted into two distinct enantiomeric domains, indexed as (1 −2, 3 6) and (3 2, 3 6) with respect to the Ag(111) surface lattice. Corresponding rotational domains are observed for each of the enantiomeric domains.