TY - JOUR
T1 - Adsorption of hydrogen atoms on the Si(100)-2×1 surface
T2 - implications for the H2 desorption mechanism
AU - Wu, Christine J.
AU - Carter, Emily A.
N1 - Funding Information:
We are grateful to the Air Force Office of Scientific Research (Grant. No. AFOSR-89-0108) for generous support of this work. EAC also acknowledges the National Science Foundation and the Camille and Henry Dreyfus Foundation for partial support this work through their Presidential Young Investigator and Distinguished New Faculty Award Programs, respectively. CJW is grateful for a Products Research Corporation Prize for Excellence in Research.
PY - 1991/10/11
Y1 - 1991/10/11
N2 - The adsorption of atomic hydrogen on the reconstructed Si(100)-2×1 surface is studied using embedded Si clusters as models of an extended Si surface. Analytic gradients of generalized valence bond (GVB) wavefunctions are used to predict equilibrium structures and harmonic vibrational frequencies; the correlation-consistent configuration interaction (CCCI) method is used to calculate heats of adsorption. We predict that the first SiH bond strength of a silicon dimer D0(SiSiH) is 86.1 kcal/mol, while the second SiH bond strength D0(HSiSiH) is 87.9 kcal/mol. Thus, no significant thermodynamic preference exists for either SiSiH or HSiSiH surface configurations, consistent with recent infrared and scanning tunneling microscopy experiments. The predicted adsorption energetics have important consequences for H2 desorption (ΔEdes=70.7 kcal/mol), with a new mechanism proposed involving H atom diffusion followed by pre-pairing desorption of two H atoms on adjacent silicon dimers in the same dimer row.
AB - The adsorption of atomic hydrogen on the reconstructed Si(100)-2×1 surface is studied using embedded Si clusters as models of an extended Si surface. Analytic gradients of generalized valence bond (GVB) wavefunctions are used to predict equilibrium structures and harmonic vibrational frequencies; the correlation-consistent configuration interaction (CCCI) method is used to calculate heats of adsorption. We predict that the first SiH bond strength of a silicon dimer D0(SiSiH) is 86.1 kcal/mol, while the second SiH bond strength D0(HSiSiH) is 87.9 kcal/mol. Thus, no significant thermodynamic preference exists for either SiSiH or HSiSiH surface configurations, consistent with recent infrared and scanning tunneling microscopy experiments. The predicted adsorption energetics have important consequences for H2 desorption (ΔEdes=70.7 kcal/mol), with a new mechanism proposed involving H atom diffusion followed by pre-pairing desorption of two H atoms on adjacent silicon dimers in the same dimer row.
UR - http://www.scopus.com/inward/record.url?scp=0001674880&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0001674880&partnerID=8YFLogxK
U2 - 10.1016/0009-2614(91)80159-U
DO - 10.1016/0009-2614(91)80159-U
M3 - Article
AN - SCOPUS:0001674880
VL - 185
SP - 172
EP - 178
JO - Chemical Physics Letters
JF - Chemical Physics Letters
SN - 0009-2614
IS - 1-2
ER -