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Titolo:
Reaction path for hydrogen adsorption and desorption on Si(100)-(2X1)
Autore:
Tok, ES; Kang, HC;
Indirizzi:
Natl Univ Singapore, Dept Mat Sci, Singapore 117543, Singapore Natl Univ Singapore Singapore Singapore 117543 ngapore 117543, Singapore Natl Univ Singapore, Dept Chem, Singapore 117543, Singapore Natl Univ Singapore Singapore Singapore 117543 ngapore 117543, Singapore
Titolo Testata:
JOURNAL OF CHEMICAL PHYSICS
fascicolo: 14, volume: 115, anno: 2001,
pagine: 6550 - 6556
SICI:
0021-9606(20011008)115:14<6550:RPFHAA>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
DISSOCIATIVE ADSORPTION; H-2 DESORPTION; MONOHYDRIDE PHASE; SURFACES; MECHANISM; DYNAMICS; SI(001);
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
19
Recensione:
Indirizzi per estratti:
Indirizzo: Kang, HC Natl Univ Singapore, Dept Mat Sci, 10 Sci Dr 4, Singapore 117543,Singapore Natl Univ Singapore 10 Sci Dr 4 Singapore Singapore 117543 apore
Citazione:
E.S. Tok e H.C. Kang, "Reaction path for hydrogen adsorption and desorption on Si(100)-(2X1)", J CHEM PHYS, 115(14), 2001, pp. 6550-6556

Abstract

The intradimer pre-paired desorption mechanism for hydrogen on Si(100)-(2 x 1) has been studied with density functional calculations using 1-dimer and 3-dimer cluster models of the surface. We find that adsorption/desorptionoccurs in a two-step process through a metastable dihydridelike intermediate, Two transition states are identified in this pathway. We confirm that the transition states are at saddle points by computing the vibrational frequencies, and that the reaction path from the monohydride to the desorbed state goes through the intermediate by performing. eigenvector-following calculations from the two transition states. The effects of clutter size-and basis set on the energetics are investigated. It is observed that energetics from 3-dimer cluster B3LYP6-311G** calculations are in reasonable agreementwith experimental data for both the adsorption and desorption barriers. Wefind an adsorption barrier of 0.65 eV and a desorption barrier of 2.94 eV:We obtain a distance of approximately 3.21 Angstrom between the silicon dimer atoms in the intermediate structure, implying a broken dimer bond, which we confirm by considering the electron density plots for the structure. Thus our results suggest that during each adsorption or desorption event thedimer bond is broken and reformed. The forces acting on the silicon dimer atoms and the hydrogen atoms along the reaction path are also investigated and these provide a picture of the coupling of the adsorption/desorption process to surface vibrations, particularly to the dimer bond breaking and reforming. This occurrence of dimer bond breaking and reforming along the reaction _ path suggests an explanation for the experimentally observed large surface-temperature activation of the adsorption process. (C) 2001 AmericanInstitute of Physics.

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Documento generato il 27/11/20 alle ore 03:43:36