Study of the helium cross-section of unsymmetric disulfide self-assembled monolayers on Au(111)

• Published in: Applied surface science Vol. 390; pp. 283 - 288
• Main Authors: Albayrak, Erol, Karabuga, Semistan, Bracco, Gianangelo, Danışman, M. Fatih
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30-12-2016
• Subjects: 11-Hydroxyundecyl decyl disulfide; 11-Hydroxyundecyl octadecyl disulfide; Cross sections; Deposition; Diffraction; Disulfides; Formations; Helium; Molecular beams; Self-assembled monolayers; Supersonic molecular beam deposition; The scattering cross sections; Unsymmetric disulfides; Unsymmetric disulfides; Supersonic molecular beam deposition; Self-assembled monolayers; The scattering cross sections; 11-Hydroxyundecyl octadecyl disulfide; 11-Hydroxyundecyl decyl disulfide
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.08.062

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•Unsymmetrtic disulfide (HDD and HOD) self assembled monolayers were grown on Au(111) by supersonic molecular beam deposition.•Helium scattering cross sections for these two different unsymmetric disulfides were determined.•A common low temperature film phase was observed for the studied disulfides.
We have investigated the formation of self-assembled monolayers (SAMs) of 11-hydroxyundecyl decyl disulfide (CH3-(CH2)9-S-S-(CH2)11-OH, HDD) and 11-hydroxyundecyl octadecyl disulfide (CH3-(CH2)17-S-S-(CH2)11-OH, HOD) produced by supersonic molecular beam deposition (SMBD). The study has been carried out by means of helium diffraction at very low film coverage. In this regime helium single molecule cross sections have been estimated in a temperature range between 100K and 450K. The results show a different behavior above 300K that has been interpreted as the starting of mobility with the formation of two thiolate moieties either linked by a gold adatom or distant enough to prevent cross section overlapping. Finally, helium diffraction patterns measured at 80K for the SAMs grown at 200K are discussed and the results support the proposed hypothesis of molecular dissociation based on the cross section data.