Comparative Molecular Resolution STM Imaging of Thiourea, Ethylthiourea, and Sulfur Self-Assembled Adlayer Structures on Silver (111)

Self-assembled adlayer structures of thiourea (TU), ethylthiourea (ETU), and sulfur (S) adsorbed on Ag(111), from neutral and alkaline aqueous solutions, are investigated with a scanning tunneling microscope operating under potential control. Voltammograms obtained under various different potential...

Descripción completa

Detalles Bibliográficos
Autores principales: Brunetti, Verónica, Blum, Bárbara, Salvarezza, Roberto Carlos, Arvia, Alejandro Jorge
Formato: Articulo
Lenguaje:Inglés
Publicado: 2003
Materias:
Química
Ciencias Exactas
Silver
Self-assembled adlayer structures
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/119208
https://pubs.acs.org/doi/full/10.1021/la034005w
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-119208
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Química
Ciencias Exactas
Silver
Self-assembled adlayer structures
spellingShingle Química
Ciencias Exactas
Silver
Self-assembled adlayer structures
Brunetti, Verónica
Blum, Bárbara
Salvarezza, Roberto Carlos
Arvia, Alejandro Jorge
Comparative Molecular Resolution STM Imaging of Thiourea, Ethylthiourea, and Sulfur Self-Assembled Adlayer Structures on Silver (111)
topic_facet Química
Ciencias Exactas
Silver
Self-assembled adlayer structures
description Self-assembled adlayer structures of thiourea (TU), ethylthiourea (ETU), and sulfur (S) adsorbed on Ag(111), from neutral and alkaline aqueous solutions, are investigated with a scanning tunneling microscope operating under potential control. Voltammograms obtained under various different potential routines are very similar for the three substances. At potentials close to −1.2 V (versus saturated calomel electrode), a (√7×√7)R19.1° adlayer structure with superlattice and nearest neighbor distances of ds = 0.76 nm and dn = 0.44 nm, respectively, is imaged, irrespective of the adsorbate molecule. In this potential region, the first pair of conjugated current peaks related to electroadsorption/desorption processes is recorded. As either the electroadsorption time is increased or the applied potential is shifted positively, self-assembled TU and S monolayers evolve into more compact structures. TU adlayers compress into hexagonal arrangements with dn = 0.33 nm, and S forms adsorbed S-trimers with the initial ordered array superstructure and coverage and shorter dn. On the other hand, ETU only presents the hexagonal arrangement with dn = 0.44 nm common to all three adsorbates at the early ordered adsorption stages. The dynamics of adsorbate patterns can be explained by the interplay of adsorbate−substrate and adsorbate−adsorbate interactions, principally hydrogen bonding for TU, steric size effects due to ethyl substituents for ETU, and a clustering process assisted by polymerization for S. As TU on Ag(111) and TU on Au(111) exhibit similar adlayer structures, the electroadsorption free energy difference was estimated from the electrodesorption voltammetric peaks. The resulting value is similar to the desorption energy differences calculated for other sulfur-containing molecules.
format Articulo
Articulo
author Brunetti, Verónica
Blum, Bárbara
Salvarezza, Roberto Carlos
Arvia, Alejandro Jorge
author_facet Brunetti, Verónica
Blum, Bárbara
Salvarezza, Roberto Carlos
Arvia, Alejandro Jorge
author_sort Brunetti, Verónica
title Comparative Molecular Resolution STM Imaging of Thiourea, Ethylthiourea, and Sulfur Self-Assembled Adlayer Structures on Silver (111)
title_short Comparative Molecular Resolution STM Imaging of Thiourea, Ethylthiourea, and Sulfur Self-Assembled Adlayer Structures on Silver (111)
title_full Comparative Molecular Resolution STM Imaging of Thiourea, Ethylthiourea, and Sulfur Self-Assembled Adlayer Structures on Silver (111)
title_fullStr Comparative Molecular Resolution STM Imaging of Thiourea, Ethylthiourea, and Sulfur Self-Assembled Adlayer Structures on Silver (111)
title_full_unstemmed Comparative Molecular Resolution STM Imaging of Thiourea, Ethylthiourea, and Sulfur Self-Assembled Adlayer Structures on Silver (111)
title_sort comparative molecular resolution stm imaging of thiourea, ethylthiourea, and sulfur self-assembled adlayer structures on silver (111)
publishDate 2003
url http://sedici.unlp.edu.ar/handle/10915/119208
https://pubs.acs.org/doi/full/10.1021/la034005w
work_keys_str_mv AT brunettiveronica comparativemolecularresolutionstmimagingofthioureaethylthioureaandsulfurselfassembledadlayerstructuresonsilver111
AT blumbarbara comparativemolecularresolutionstmimagingofthioureaethylthioureaandsulfurselfassembledadlayerstructuresonsilver111
AT salvarezzarobertocarlos comparativemolecularresolutionstmimagingofthioureaethylthioureaandsulfurselfassembledadlayerstructuresonsilver111
AT arviaalejandrojorge comparativemolecularresolutionstmimagingofthioureaethylthioureaandsulfurselfassembledadlayerstructuresonsilver111
bdutipo_str Repositorios
_version_ 1764820448009256960

Ejemplares similares