FisMat2017 - Submission - View

Abstract's title: Study of stability of Ruthenocene on Ag(111) and Cu(111) by means of X-ray Photoemission and Absorption Spectroscopies
Submitting author: Alberto Verdini
Affiliation: CNR-IOM
Affiliation Address: c/o Area Science Park s.s. 14 km 163.5 Basovizza 34149 Trieste - Italy
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: Marco Caputo (Swiss Light Source Paul Scherrer Institute CH-5232 Villigen-PSI Switzerland), G. Fratesi (Dipartimento di Fisica Universita` degli Studi di Milano Via Celoria 16, 20133 Milano, Italy) , A. Cossaro (CNR-IOM, c/o Area Science Park s.s. 14 km 163.5 Basovizza 34149 Trieste, Italy) , G. Di Santo (ELETTRA - Sincrotrone Trieste S.C.p.A. s.s. 14 - km 163,5 in AREA Science Park 34149 Basovizza, Trieste, Italy) , M. Panighel (CNR-IOM, c/o Area Science Park s.s. 14 km 163.5 Basovizza 34149 Trieste, Italy), L. Floreano (CNR-IOM, c/o Area Science Park s.s. 14 km 163.5 Basovizza 34149 Trieste, Italy), A. Goldoni (ELETTRA - Sincrotrone Trieste S.C.p.A. s.s. 14 - km 163,5 in AREA Science Park 34149 Basovizza, Trieste, Italy)
Abstract

The discovery of Ferrocene molecule - Fe(C5H5)2, which lead to the Nobel Prize in 1973, gave a fundamental boost to the organometallic chemistry. Metallocenes show a “sandwich structure”, which doesn’t exist in nature, with two ring-shaped carbon compounds enclosing a metallic atom. An increasing interest on these compounds has been raised recently, mainly due to the possibility to exploit spin dependent-effects of the magnetic metal atoms and for the production of metal-molecule layers in molecular electronics. Among all the metallocenes, the most studied is Ferrocene. It is known to weakly physisorb on metal surfaces and to desorb at temperatures around 250K. On the other hand, almost no experimental data is available for the Ruthenocene, for which an higher stability is expected thanks to the higher ionization potential. In order to fill this lack of data, we decided to study the desorption of Ruthenocene deposited on Cu(111) and Ag(111) as a function of the temperature. By exploiting the fast- X-ray Photoemission Spectroscopy (XPS) measurement capability at the ALOISA beamline (Elettra Synchrotron Facility), we followed the evolution of the C 1s and Ru 3d core level peaks by raising the temperature from 220K up to room temperature. We observe a similar behavior for both substrates, with a desorption temperature of 250 K for Ag(111) and 280 K for Cu(111). Nevertheless, while for the Ag(111) case XPS indicates an almost complete desorption at room temperature, for the Cu(111) case data show clearly still presence of molecules on the surface. This is a clear indication of a stronger interaction between Ruthenocene/Cu rather than Ruthenocene/Ag. In the case of Ruthenocene/Ag(111), we extended the study by means of the Near Edge X-ray Absorption Spectroscopy (NEXAFS), collecting the spectra on the as-deposited Ruthenocene and on the Submonolayer present at Room Temperature. The dichroism obtained from the data clearly shows that the pristine film is much more ordered than the submonolayer.