AVS 52nd International Symposium
    Surface Science Thursday Sessions
       Session SS2-ThA

Paper SS2-ThA5
Gas-Surface Reaction Dynamics of NO on Iron Phthalocyanine Thin Films

Thursday, November 3, 2005, 3:20 pm, Room 203

Session: Gas-Surface Reaction Dynamics
Presenter: S.R. Bishop, University of California, San Diego
Authors: S.R. Bishop, University of California, San Diego
N.L. Tran, University of California, San Diego
G.C. Poon, University of California, San Diego
A.C. Kummel, University of California, San Diego
Correspondent: Click to Email
Metallophthalocyanines (MPc) have been proposed for use in chemically sensitive field effect transistor (chem-FET) detectors for the measurement of ambient analytes such as NO@sub x@, NH@sub 3@, and O@sub 3@. However, the adsorption energies and mechanisms of the reaction between these gases and MPc thin films have not been studied. We have investigated the reaction dynamics between NO and monolayer Iron Phthalocyanine (FePc) grown on clean Au(111) surface. The sticking probabilities of 0.11 eV monoenergetic molecular beam of NO were measured on both clean Au(111) and ordered 6x6 monolayer-FePc deposited on clean Au(111) as a function of surface temperature. NO sticking on the Au(111) surface occurs through a precursor-mediated physisorption pathway. In comparison, NO sticking on the FePc film occurs via multiple pathways: direct chemisorption to the metal center and precursor-mediated physisorption. Although the metal center of the molecule accounts for only ~3% of the surface, the direct chemisorption pathway has a sticking probability of ~20%. This suggests that the NO molecules are steered to the reactive metal centers by other portions of the FePc molecule. By using a high translational energy molecular beam, the direct chemisorption pathway will be selectively probed.