A SSIMS and TPD Study of tert-Butylacetylacetate Adsorption on Si(100)
Resource
The Journal of Physical Chemistry B 105 (5): 994-1002
Journal
The Journal of Physical Chemistry B
Journal Volume
105
Journal Issue
5
Pages
994-1002
Date Issued
2001
Date
2001
Author(s)
Abstract
Adsorption and decomposition of tert-butylacetylacetate (tBAA) on Si(100) have been investigated using static secondary ion mass spectrometry and temperature-programmed desorption. At low doses, all tBAA molecules dissociate readily upon adsorption on the surface at temperatures as low as ?160 �XC. The dissociation may occur through tBAA bonding via the ester oxygen or the carbonyl group to the surface. The bond scission occurring at the tBuO?CO bond leads to the formation of surface tert-butoxide. Further dehydrogenation can take place to yield isobutene and surface hydroxyl species. Subsequent heating of the substrate causes the hydroxyl to decompose, and the resulting substoichiometric silicon oxide sublimes as SiO. The surface-induced bond scission also occurs at the OC?CCO bond of the tBAA diketo moiety to produce isobutene. In addition, the OC?CCO bond scission induced by tBAA surface bonding, mainly via its carboxylic keto oxygen, affords acetaldehyde radical, whereas that induced mainly via the aceto oxygen yields carbon dioxide and isopropenoxy species. An enol?keto conversion takes place when isopropenoxy species acquire surface hydrogen to yield acetone, even at low substrate temperature of less than ?126 �XC. The aceto oxygen pathway dominates the cleavage of the OC?CCO bond. Increasing substrate temperature also causes the surface tert-butyl fragments to further react through different �]-hydride elimination pathways, forming isobutene, which is either in the gaseous state or bound to the surface in a di-�m configuration.
SDGs
Type
journal article
File(s)![Thumbnail Image]()
Loading...
Name
10.pdf
Size
118.85 KB
Format
Adobe PDF
Checksum
(MD5):3ec1ec26480f484af105e938b3780faf