Adsorption heights and bonding strength of organic molecules on a Pb-Ag surface alloy

DOI: 10.1103/PhysRevB.94.235436

Authors: Benjamin Stadtmueller (University of Kaiserslautern; Graduate School of Excellence Materials Science in Mainz) , Norman Haag (University of Kaiserslautern) , Johannes Seidel (University of Kaiserslautern) , Gerben Van Straaten (Peter Grunberg Institut (PGI-3); Julich-Aachen Research Alliance (JARA) - Fundamentals of Future Information Technology) , Markus Franke (Peter Grunberg Institut (PGI-3); Julich-Aachen Research Alliance (JARA) - Fundamentals of Future Information Technology) , Christian Kumpf (Peter Grunberg Institut (PGI-3); Julich-Aachen Research Alliance (JARA) - Fundamentals of Future Information Technology) , Mirko Cinchetti (Technische Universitat Dortmund) , Martin Aeschlimann (University of Kaiserslautern)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 94 , PAGES 235436

State: Published (Approved)
Published: December 2016
Diamond Proposal Number(s): 10370 , 11915

Abstract: The understanding of the fundamental geometric and electronic properties of metal-organic hybrid interfaces is a key issue on the way to improving the performance of organic electronic and spintronic devices. Here, we studied the adsorption heights of copper-II-phthalocyanine (CuPc) and 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) on a Pb 1 Ag 2 surface alloy on Ag(111) using the normal-incidence x-ray standing waves technique. We find a significantly larger adsorption height of both molecules on the Pb-Ag surface alloy compared to the bare Ag(111) surface which is caused by the larger size of Pb. This increased adsorption height suppresses the partial chemical interaction of both molecules with Ag surface atoms. Instead, CuPc and PTCDA molecules bond only to the Pb atoms with different interaction strength ranging from a van der Waals–like interaction for CuPc to a weak chemical interaction with additional local bonds for PTCDA. The different adsorption heights for CuPc and PTCDA on Pb 1 Ag 2 are the result of local site-specific molecule-surface bonds mediated by functional molecular groups and the different charge donating and accepting character of CuPc and PTCDA.

Subject Areas: Materials, Physics, Chemistry


Instruments: I09-Surface and Interface Structural Analysis