| AVS 55th International Symposium & Exhibition | |
| Surface Science | Thursday Sessions |
| Session SS1+NC-ThA |
| Session: | Water-Surface Interactions |
| Presenter: | J. Schnadt, Lund University, Sweden |
| Authors: | C. Isvoranu, Lund University, Sweden E. Ataman, Lund University, Sweden K. Schulte, Lund University, Sweden A. Rienzo, University of Nottingham, UK G. Magnano, University of Nottingham, UK J.N. O'Shea, University of Nottingham, UK J.N. Andersen, Lund University, Sweden J. Schnadt, Lund University, Sweden |
| Correspondent: | Click to Email |
Phthalocyanines are an extensively studied class of molecules due to their chemical and thermal stability and high polarizability. These characteristics make the phthalocyanines and related molecules interesting for a wide range of applications such as in molecular electronics, gas sensing devices, or as cathode and/or anode materials in fuel cells. Often, in such applications the molecules will be in contact with either liquid water as an important component of the application or with water from the ambient atmosphere. In spite of the ubiquity of the water – molecule interaction, investigations of the atomic-scale properties of the interaction of organic and organometallic molecules with water in general and of phthalocyanines with water in particular are scarce. Here, we have studied the adsorption of iron phthalocyanines on Au(111) by x-ray photoelectron and x-ray absorption spectroscopies at both sub- and full monolayer coverages and we have characterized the interaction of the different preparations with small amounts of water. For the water-free preparations, the results indicate that the full monolayer is dominated by a single molecular species, while several distinct species are observed for the submonolayer coverages. Tentatively, these different species are assigned to structures previously observed by scanning tunnelling microscopy (STM).1 The present results show clearly that the interaction between the substrate and adsorbate differ strongly between the submonolayer and full monolayer structures, with the interaction appearing considerably stronger for the submonolayer structures. Iron phthalocyanine monolayers on Au(111) are inert to water with no change observed in the spectral characteristics of the molecular layer when exposed to water. Quite in contrast, the submonolayers exhibit strong modifications of the spectral appearances, which can be assigned to an interaction between the molecular adsorbates and water. Surprisingly, the observed chemical shifts point to a more subtle interaction of water with the iron phthalocyanines than a mere hydrogen bond formation between the water and the phthalocyanines.
1 Z.H. Cheng, L. Gao, Z.T. Deng, N. Jiang, Q. Liu, D.X. Shi, S.X. Du, H.M. Guo, and H.-J. Gao, J. Phys. Chem. C 111 (2007) 9240.