TY - JOUR
T1 - Infrared and X-ray photoelectron spectroscopic studies of the reactions of hydrogen-terminated crystalline Si(111) and Si(100) surfaces with Br2, I2, and ferrocenium in alcohol solvents
AU - Haber, Joel A.
AU - Lewis, Nathan S.
N1 - Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2002/4/11
Y1 - 2002/4/11
N2 - The reaction chemistry of H-terminated crystalline Si(111) and Si(100) surfaces in CH3OH, CD3OD, CF3(CH2)3OH, C4H9OH, and C4D9OD solutions containing ferrocenium (Fc+)-BF4, I2, or Br2 was monitored using X-ray photoelectron (XP) spectroscopy and infrared (IR) spectroscopy. Addition of the one-electron oxidant Fc+, or addition of the oxidizing species I2 or Br2, produced diagnostic changes in the IR spectra that clearly indicated formation of surficial Si-OR groups. XPS data confirmed the conclusions of the IR studies: Under our reaction conditions, no detectable reaction occurred without the presence of the oxidant. The data are consistent with oxidative activation of the surficial Si-H bonds toward nucleophilic attack by the alcohols. The reaction chemistry was generally similar on (111)-and (100)-oriented Si surfaces, although some differences were observed in the ratio of reaction products on the two different surface orientations. Alkoxylated surfaces were also prepared by a two-step process in which the surface was first chlorinated and then reacted with LiOCH3, LiOCD3, or LiO(CH2)3CF3. The data indicate that formation of silicon-halogen bonding alone is not sufficient to provide a robust correlation between the electronic and chemical properties of such crystalline Si surfaces and that formation of silicon-alkoxyl bonds is a common motif for surfaces often used in electronic and electrochemical studies of Si.
AB - The reaction chemistry of H-terminated crystalline Si(111) and Si(100) surfaces in CH3OH, CD3OD, CF3(CH2)3OH, C4H9OH, and C4D9OD solutions containing ferrocenium (Fc+)-BF4, I2, or Br2 was monitored using X-ray photoelectron (XP) spectroscopy and infrared (IR) spectroscopy. Addition of the one-electron oxidant Fc+, or addition of the oxidizing species I2 or Br2, produced diagnostic changes in the IR spectra that clearly indicated formation of surficial Si-OR groups. XPS data confirmed the conclusions of the IR studies: Under our reaction conditions, no detectable reaction occurred without the presence of the oxidant. The data are consistent with oxidative activation of the surficial Si-H bonds toward nucleophilic attack by the alcohols. The reaction chemistry was generally similar on (111)-and (100)-oriented Si surfaces, although some differences were observed in the ratio of reaction products on the two different surface orientations. Alkoxylated surfaces were also prepared by a two-step process in which the surface was first chlorinated and then reacted with LiOCH3, LiOCD3, or LiO(CH2)3CF3. The data indicate that formation of silicon-halogen bonding alone is not sufficient to provide a robust correlation between the electronic and chemical properties of such crystalline Si surfaces and that formation of silicon-alkoxyl bonds is a common motif for surfaces often used in electronic and electrochemical studies of Si.
UR - http://www.scopus.com/inward/record.url?scp=0037061512&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037061512&partnerID=8YFLogxK
U2 - 10.1021/jp0102872
DO - 10.1021/jp0102872
M3 - Article
AN - SCOPUS:0037061512
VL - 106
SP - 3639
EP - 3656
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1520-6106
IS - 14
ER -