THIOETHYLPYRROLE MONOLAYERS ON GOLD - A SPECTROSCOPIC STUDY IN ULTRAHIGH-VACUUM

Citation
H. Kariis et al., THIOETHYLPYRROLE MONOLAYERS ON GOLD - A SPECTROSCOPIC STUDY IN ULTRAHIGH-VACUUM, JOURNAL OF PHYSICAL CHEMISTRY B, 102(34), 1998, pp. 6529-6538
Citations number
36
Categorie Soggetti
Chemistry Physical
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
15206106 → ACNP
Volume
102
Issue
34
Year of publication
1998
Pages
6529 - 6538
Database
ISI
SICI code
1089-5647(1998)102:34<6529:TMOG-A>2.0.ZU;2-F
Abstract
The adsorption of 3-(2-thioethyl)pyrrole (3-TEP) and 1-(2-thioethyl)py rrole (1-TEP) on gold has been studied in ultrahigh vacuum with infrar ed reflection absorption spectroscopy, X-ray photoelectron spectroscop y, and temperature-programmed desorption mass spectroscopy. Deposition s were made from liquid phase at atmospheric pressure, from gas phase in ultrahigh vacuum: and from gas phase at atmospheric pressure. Both molecules were found to chemisorb to the gold surface regardless of th e deposition method. Most of the 3-TEP, however, broke up, losing the pyrrole ring as it adsorbed on the surface. Both monolayers were sensi tive to oxygen and oxidized quickly if stored in air. Deposition of 1- TEP from solution or vapor in air gave a higher desorption peak temper ature than deposition from gas phase in UHV. The masses of the desorbi ng fragments that were detected from the heated monolayers were smalle r than those seen upon introducing 1-TEP gas into the UHV system, reve aling that a partial decomposition of the adsorbed molecules occurred prior to or at desorption. Some samples were electrochemically cycled to positive potentials to investigate the stability of the monolayers. A large fraction of the 1-TEP and 3-TEP stayed on the surface when cy cled to 0.8 V, but some oxidation, fragmentation, and desorption were seen at higher potentials.