AVS 51st International Symposium
    Organic Films and Devices Wednesday Sessions
       Session OF+EM-WeM

Paper OF+EM-WeM11
UHV-STM/XPS Studies of ACA Molecular Assemblies on Ag(111)

Wednesday, November 17, 2004, 11:40 am, Room 304C

Session: Molecular and Organic Films and Devices - Electronics
Presenter: B. Xu, University of Maryland
Authors: B. Xu, University of Maryland
D. Evans, University of Maryland
B. Varughese, University of Maryland
J. Reutt-Robey, University of Maryland
Correspondent: Click to Email
The structures of acridine carboxylic acid (ACA) molecular films grown on Ag (111) by physical vapor deposition were characterized using UHV-STM and XPS. On large terraces (with terrace-spanning diameters exceeding 100 nm), ACA molecules form well ordered 2-d islands. The driving force for island formation is attributed to hydrogen-bond formation between ACA molecules (attractive along [1-10] ) and substrate mediated attraction along [11-2]. XPS experiments reveal that H-bond interaction involves the ring nitrogen acting as the H-bond acceptor(O-H...N). On narrow terraces (~3 nm in width) completely different ACA structures are observed. In these confined regions, ACA molecules assemble into dimers, which are further organized into coverage-dependent adlayer structures. Finally, we report the observation of bi-layer and tri-layer structures.