Title of article :
Molecular conformation and electronic properties of protoporphyrin-IX self-assembled monolayers adsorbed on a Pt(1 1 1) surface
Author/Authors :
Humbert، نويسنده , , C. and Volcke، نويسنده , , C. and Sartenaer، نويسنده , , Y. and Peremans، نويسنده , , A. and Thiry، نويسنده , , P.A. and Dreesen، نويسنده , , L.، نويسنده ,
Issue Information :
هفته نامه با شماره پیاپی سال 2006
Pages :
8
From page :
3702
To page :
3709
Abstract :
Monolayers of protoporphyrin-IX molecules are prepared on a Pt(1 1 1) surface by a self-assembly process in order to manufacture organic devices with controlled electronic properties. Scanning tunnelling microscopy (STM) and two-colour sum-frequency generation (2C-SFG) are performed ex situ in ambient air, in order to characterize their molecular conformation and electronic properties at the monolayer level, respectively. STM measurements performed with functionalized gold tips reveal a high covering rate of the metal surface. 2C-SFG measurements highlight CH stretching modes of vinyl substituted groups (RCHCH2) in the 2800–3200 cm−1 infrared spectral range and particular electronic features in the visible spectral range, i.e. a Soret band red shift and band separation compared to the liquid phase. Moreover, similar measurements are performed on Zn(II)Protoporphyrin-IX and 5-[p-(6-mercaptohexoxy)-phenyl]-10,15,20-triphenylporphin films for comparison. These results suggest a film conformation with the molecules having different tilt angles with respect to the substrate normal, depending on the ion metal presence or the chain length bonded to the porphyrin moiety.
Keywords :
Mercaptoporphyrins , Sum-frequency generation , Monolayers , Protoporphyrins , STM
Journal title :
Surface Science
Serial Year :
2006
Journal title :
Surface Science
Record number :
1699184
Link To Document :
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