Linked Life Data

19206601

Source:http://linkedlifedata.com/resource/pubmed/id/19206601

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2009-2-11
pubmed:abstractText
An earlier experimental study by scanning tunneling microscopy (STM) from this laboratory described the use of "localized reaction" as a means to the electron- or photon-imprinting of self-assembled patterns of CH(3)Br(ad) as covalently bound Br-Si(s) at Si(111)-7x7. Here we show that the thermal surface bromination reaction by CH(3)Br(ad) is also highly localized, and present a detailed ab initio dynamical model for the reaction, using DFT. Localization is seen to be due to the coexistence in the reactive transition-state of the neighboring bonds being broken (C-Br) and formed (Br-Si). Both experiment and theory are consistent with a low energy-barrier, E(a) approximately 0.2 eV, for the thermal bromination of Si(111) by CH(3)Br(ad), and also for the desorption of intact CH(3)Br(g) (E(des) approximately 0.2 eV). Two physisorbed states of CH(3)Br(ad)/Si(111) (I and II) are distinguishable by STM at 50 K by their differing displacement from the underlying Si adatom. These states can be identified with similarly displaced states in the STM images simulated by DFT. At the elevated temperature of 80 K, a markedly displaced physisorbed state (III) appears in the STM image, indicated by DFT to have a configuration encountered along the reaction path immediately prior to the transition state. The electron-induced bromination of Si(111) by CH(3)Br(ad), and also electron-induced molecular desorption, are examined as a function of the energy of the incident electron, giving for both processes a threshold energy of E(e) approximately 1.8 eV in accord with ab initio theory, and a substantial yield of 10(-6) to 10(-5) Br-Si(s)/electron.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
1936-086X
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
2
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
699-706
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Molecular dynamics of localized reaction, experiment and theory: methyl bromide on Si(111)-7x7.
pubmed:affiliation
Centre for the Physics of Materials and Department of Physics, McGill University, Montréal, Québec, Canada.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't