Metal tetraphenylporphyrins (MTPPs, with M = Zn, Co) deposited on an oxygen-passivated Fe substrate, namely Fe(0 0 1)-p(1 x 1)O, were studied to understand the mechanism of molecular self-assembling on ultrathin metaloxide films. These were characterized by photoemission spectroscopy (PES) and low energy electron diffraction (LEED).Heterogeneous MTPP monolayers (ZnTPP + CoTPP) were grown at room temperature by depositing a sub-monolayer of ZnTPP on Fe(0 0 1)-p(1 x 1)O followed by a sub-monolayer of CoTPP or vice-versa, or by codeposition. Homogeneous layers are characterized by markedly different molecular superstructures, as shown by LEED. Conversely, heterogeneous monolayers reflected an even more complex behavior: in particular, it was observed that the deposition of a small amount of CoTPP before or simultaneous to the dosing of ZnTPP molecules was able to stabilize a (5 x 5)R37 degrees diffraction pattern, characteristic of homogeneous CoTPP, whereas homogeneous ZnTPP layers are associated to a straight (5 x 5) one. The observed differences in the ordering of the molecular self-assembling as a consequence of combining the two MTPPs highlights a significant influence of one MTPP over the other depending upon the central metal ion and not upon the molecular skeleton.
Porphyrin central metal ion driven self-assembling in heterogeneous ZnTPP – CoTPP films grown on Fe(0 0 1)-p(1 × 1)O
Majumdar I.;Goto F.;Calloni A.;Albani G.;Duo' L.;Finazzi M.;Ciccacci F.;Bussetti G.
2023-01-01
Abstract
Metal tetraphenylporphyrins (MTPPs, with M = Zn, Co) deposited on an oxygen-passivated Fe substrate, namely Fe(0 0 1)-p(1 x 1)O, were studied to understand the mechanism of molecular self-assembling on ultrathin metaloxide films. These were characterized by photoemission spectroscopy (PES) and low energy electron diffraction (LEED).Heterogeneous MTPP monolayers (ZnTPP + CoTPP) were grown at room temperature by depositing a sub-monolayer of ZnTPP on Fe(0 0 1)-p(1 x 1)O followed by a sub-monolayer of CoTPP or vice-versa, or by codeposition. Homogeneous layers are characterized by markedly different molecular superstructures, as shown by LEED. Conversely, heterogeneous monolayers reflected an even more complex behavior: in particular, it was observed that the deposition of a small amount of CoTPP before or simultaneous to the dosing of ZnTPP molecules was able to stabilize a (5 x 5)R37 degrees diffraction pattern, characteristic of homogeneous CoTPP, whereas homogeneous ZnTPP layers are associated to a straight (5 x 5) one. The observed differences in the ordering of the molecular self-assembling as a consequence of combining the two MTPPs highlights a significant influence of one MTPP over the other depending upon the central metal ion and not upon the molecular skeleton.File | Dimensione | Formato | |
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