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1589000 
Journal Article 
Adsorption of L-cysteine on rutile TiO2(110) 
Ataman, E; Isvoranu, C; Knudsen, Jan; Schulte, K; Andersen, JN; Schnadt, J 
2011 
1 
Surface Science
ISSN: 0039-6028 
605 
1-2 
179-186 
WOS:000286021000026 
We have used X-ray photoelectron spectroscopy to study the
adsorption of L-cysteine on a rutile TiO2(110) surface at room temperature and -65 degrees C. For
the molecules in direct contact with the surface our results suggest that the molecules bind
dissociatively to the fivefold-coordinated Ti atoms of the surface through their deprotonated
carboxylic groups. A second, dissociative interaction occurs between the molecular thiol groups
and the surface. It is attributed to a dissociative bond to the bridging oxygen vacancies. Most
likely, the thiol groups are deprotonated and a bond is formed between the thiolates and defects.
In an alternative scenario, the C-S bond is cleaved and atomic sulfur binds to the defects. With
regard to the molecular amino groups, they remain neutral at the lowest investigated coverages
(0.3-0.5 ML), but already starting from around 0.7 ML nominal coverage protons are being
transferred to them. The fraction of protonated amino groups increases with coverage and becomes
dominating in multilayers prepared at room temperature and -65 degrees C. In these multilayers
the carboxylic groups are deprotonated. (C) 2010 Elsevier B.V. All tights reserved. 
L-cysteine; X-ray photoelectron spectroscopy; Rutile TiO2(110); Amino acid; Adsorption