Dissociative adsorption of CH₃X (X = Br and Cl) on a silicon(100) surface revisited by density functional theory

TY - JOUR

T1 - Dissociative adsorption of CH3X (X = Br and Cl) on a silicon(100) surface revisited by density functional theory

AU - Wang, Chen Guang

AU - Huang, Kai

AU - Ji, Wei

N1 - Publisher Copyright: © 2014 AIP Publishing LLC.

PY - 2014/11/7

Y1 - 2014/11/7

N2 - During the dissociative adsorption on a solid surface, the substrate usually participates in a passive manner to accommodate fragments produced upon the cleavage of the internal bond(s) of a (transient) molecular adsorbate. This simple picture, however, neglects the flexibility of surface atoms. Here, we report a Density Functional Theory study to revisit our early studies of the dissociative adsorption of CH3X (X = Br and Cl) on Si(100). We have identified a new reaction pathway, which involves a flip of a silicon dimer; this new pathway agrees better with experiments. For our main exemplar of CH3Br, insights have been gained using a simple model that involves a three-atom reactive center, Br-C-Si. When the silicon dimer flips, the interaction between C and Si in the Br-C-Si center is enhanced, evident in the increased energy-split of the frontier orbitals. We also examine how the dissociation dynamics of CH3Br is altered on a heterodimer (Si-Al, Si-P, and Si-Ge) in a Si(100) surface. In each case, we conclude, on the basis of computed reaction pathways, that no heterodimer flipping is involved before the system transverses the transition state to dissociative adsorption.

AB - During the dissociative adsorption on a solid surface, the substrate usually participates in a passive manner to accommodate fragments produced upon the cleavage of the internal bond(s) of a (transient) molecular adsorbate. This simple picture, however, neglects the flexibility of surface atoms. Here, we report a Density Functional Theory study to revisit our early studies of the dissociative adsorption of CH3X (X = Br and Cl) on Si(100). We have identified a new reaction pathway, which involves a flip of a silicon dimer; this new pathway agrees better with experiments. For our main exemplar of CH3Br, insights have been gained using a simple model that involves a three-atom reactive center, Br-C-Si. When the silicon dimer flips, the interaction between C and Si in the Br-C-Si center is enhanced, evident in the increased energy-split of the frontier orbitals. We also examine how the dissociation dynamics of CH3Br is altered on a heterodimer (Si-Al, Si-P, and Si-Ge) in a Si(100) surface. In each case, we conclude, on the basis of computed reaction pathways, that no heterodimer flipping is involved before the system transverses the transition state to dissociative adsorption.

UR - http://www.scopus.com/inward/record.url?scp=84908674608&partnerID=8YFLogxK

U2 - 10.1063/1.4899841

DO - 10.1063/1.4899841

M3 - 文章

AN - SCOPUS:84908674608

SN - 0021-9606

VL - 141

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

IS - 17

M1 - 174701

ER -