XPS and EXAFS studies of the reactions of Co(III) ammine complexes with GaAs surfaces

Bruce J. Tufts, Ian L. Abrahams, Catherine E. Caley, Sharon R. Lunt, Gordon M. Miskelly, Nathan S Lewis, Patrick G. Santangelo, Nathan S. Lewis, A. Lawrence Roe, Keith O. Hodgson

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

The chemisorption of Co(II) and Co(III) complexes onto GaAs surfaces has been investigated by X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy, and radiotracer techniques. XPS of (100)-oriented n-GaAs single crystals exposed to aqueous (pH > 10) [CoIII(NH3)5X]n+ (X = NH3, Br-, HO-) solutions indicated the deposition of a Co(II)-oxo overlayer of approximate stoichiometry Co(OH)2, with a coverage of (0.2-2.4) × 10-8 mol of Co/cm2 projected area of GaAs. The reaction stoichiometry between Co(III) and GaAs was confirmed by quantitative chemical and X-ray fluorescence analysis, as well as by XPS analysis. X-ray absorption spectroscopy indicated that the oxidation state of the adsorbed Co (from either Co(III) or Co(II) complexes) from aqueous pH = 12 electrolytes was Co(II). Extended X-ray absorption fine structure (EXAFS) spectroscopy at 298 K in contact with aqueous 0.010 M KOH indicated that the Co had (6 ± 1) O or N scatterers at (2.08 ± 0.05) Å and (7 ± 1) Co (or possibly Ga or As) scatterers at (3.13 ± 0.05) Å. EXAFS and XPS methods also indicated that exposure of the Co-GaAs surfaces to 1.0 M KOH-0.8 M Se2--0.1 M Se22- for photoelectrochemical measurements yielded a new Co surface phase, with an approximate composition of CoSe1.8.

Original languageEnglish
Pages (from-to)5123-5136
Number of pages14
JournalJournal of the American Chemical Society
Volume112
Issue number13
Publication statusPublished - Jun 20 1990

Fingerprint

Photoelectron Spectroscopy
X ray absorption
X ray photoelectron spectroscopy
X-Rays
X ray absorption spectroscopy
X-Ray Absorption Spectroscopy
Stoichiometry
Extended X ray absorption fine structure spectroscopy
Chemisorption
Fluorescence
Electrolytes
Single crystals
Spectrum Analysis
X rays
Oxidation
gallium arsenide
Chemical analysis

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Tufts, B. J., Abrahams, I. L., Caley, C. E., Lunt, S. R., Miskelly, G. M., Lewis, N. S., ... Hodgson, K. O. (1990). XPS and EXAFS studies of the reactions of Co(III) ammine complexes with GaAs surfaces. Journal of the American Chemical Society, 112(13), 5123-5136.

XPS and EXAFS studies of the reactions of Co(III) ammine complexes with GaAs surfaces. / Tufts, Bruce J.; Abrahams, Ian L.; Caley, Catherine E.; Lunt, Sharon R.; Miskelly, Gordon M.; Lewis, Nathan S; Santangelo, Patrick G.; Lewis, Nathan S.; Roe, A. Lawrence; Hodgson, Keith O.

In: Journal of the American Chemical Society, Vol. 112, No. 13, 20.06.1990, p. 5123-5136.

Research output: Contribution to journalArticle

Tufts, BJ, Abrahams, IL, Caley, CE, Lunt, SR, Miskelly, GM, Lewis, NS, Santangelo, PG, Lewis, NS, Roe, AL & Hodgson, KO 1990, 'XPS and EXAFS studies of the reactions of Co(III) ammine complexes with GaAs surfaces', Journal of the American Chemical Society, vol. 112, no. 13, pp. 5123-5136.
Tufts BJ, Abrahams IL, Caley CE, Lunt SR, Miskelly GM, Lewis NS et al. XPS and EXAFS studies of the reactions of Co(III) ammine complexes with GaAs surfaces. Journal of the American Chemical Society. 1990 Jun 20;112(13):5123-5136.
Tufts, Bruce J. ; Abrahams, Ian L. ; Caley, Catherine E. ; Lunt, Sharon R. ; Miskelly, Gordon M. ; Lewis, Nathan S ; Santangelo, Patrick G. ; Lewis, Nathan S. ; Roe, A. Lawrence ; Hodgson, Keith O. / XPS and EXAFS studies of the reactions of Co(III) ammine complexes with GaAs surfaces. In: Journal of the American Chemical Society. 1990 ; Vol. 112, No. 13. pp. 5123-5136.
@article{b40ca8ec844842369fdc3da73da0fc09,
title = "XPS and EXAFS studies of the reactions of Co(III) ammine complexes with GaAs surfaces",
abstract = "The chemisorption of Co(II) and Co(III) complexes onto GaAs surfaces has been investigated by X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy, and radiotracer techniques. XPS of (100)-oriented n-GaAs single crystals exposed to aqueous (pH > 10) [CoIII(NH3)5X]n+ (X = NH3, Br-, HO-) solutions indicated the deposition of a Co(II)-oxo overlayer of approximate stoichiometry Co(OH)2, with a coverage of (0.2-2.4) × 10-8 mol of Co/cm2 projected area of GaAs. The reaction stoichiometry between Co(III) and GaAs was confirmed by quantitative chemical and X-ray fluorescence analysis, as well as by XPS analysis. X-ray absorption spectroscopy indicated that the oxidation state of the adsorbed Co (from either Co(III) or Co(II) complexes) from aqueous pH = 12 electrolytes was Co(II). Extended X-ray absorption fine structure (EXAFS) spectroscopy at 298 K in contact with aqueous 0.010 M KOH indicated that the Co had (6 ± 1) O or N scatterers at (2.08 ± 0.05) {\AA} and (7 ± 1) Co (or possibly Ga or As) scatterers at (3.13 ± 0.05) {\AA}. EXAFS and XPS methods also indicated that exposure of the Co-GaAs surfaces to 1.0 M KOH-0.8 M Se2--0.1 M Se22- for photoelectrochemical measurements yielded a new Co surface phase, with an approximate composition of CoSe1.8.",
author = "Tufts, {Bruce J.} and Abrahams, {Ian L.} and Caley, {Catherine E.} and Lunt, {Sharon R.} and Miskelly, {Gordon M.} and Lewis, {Nathan S} and Santangelo, {Patrick G.} and Lewis, {Nathan S.} and Roe, {A. Lawrence} and Hodgson, {Keith O.}",
year = "1990",
month = "6",
day = "20",
language = "English",
volume = "112",
pages = "5123--5136",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "13",

}

TY - JOUR

T1 - XPS and EXAFS studies of the reactions of Co(III) ammine complexes with GaAs surfaces

AU - Tufts, Bruce J.

AU - Abrahams, Ian L.

AU - Caley, Catherine E.

AU - Lunt, Sharon R.

AU - Miskelly, Gordon M.

AU - Lewis, Nathan S

AU - Santangelo, Patrick G.

AU - Lewis, Nathan S.

AU - Roe, A. Lawrence

AU - Hodgson, Keith O.

PY - 1990/6/20

Y1 - 1990/6/20

N2 - The chemisorption of Co(II) and Co(III) complexes onto GaAs surfaces has been investigated by X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy, and radiotracer techniques. XPS of (100)-oriented n-GaAs single crystals exposed to aqueous (pH > 10) [CoIII(NH3)5X]n+ (X = NH3, Br-, HO-) solutions indicated the deposition of a Co(II)-oxo overlayer of approximate stoichiometry Co(OH)2, with a coverage of (0.2-2.4) × 10-8 mol of Co/cm2 projected area of GaAs. The reaction stoichiometry between Co(III) and GaAs was confirmed by quantitative chemical and X-ray fluorescence analysis, as well as by XPS analysis. X-ray absorption spectroscopy indicated that the oxidation state of the adsorbed Co (from either Co(III) or Co(II) complexes) from aqueous pH = 12 electrolytes was Co(II). Extended X-ray absorption fine structure (EXAFS) spectroscopy at 298 K in contact with aqueous 0.010 M KOH indicated that the Co had (6 ± 1) O or N scatterers at (2.08 ± 0.05) Å and (7 ± 1) Co (or possibly Ga or As) scatterers at (3.13 ± 0.05) Å. EXAFS and XPS methods also indicated that exposure of the Co-GaAs surfaces to 1.0 M KOH-0.8 M Se2--0.1 M Se22- for photoelectrochemical measurements yielded a new Co surface phase, with an approximate composition of CoSe1.8.

AB - The chemisorption of Co(II) and Co(III) complexes onto GaAs surfaces has been investigated by X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy, and radiotracer techniques. XPS of (100)-oriented n-GaAs single crystals exposed to aqueous (pH > 10) [CoIII(NH3)5X]n+ (X = NH3, Br-, HO-) solutions indicated the deposition of a Co(II)-oxo overlayer of approximate stoichiometry Co(OH)2, with a coverage of (0.2-2.4) × 10-8 mol of Co/cm2 projected area of GaAs. The reaction stoichiometry between Co(III) and GaAs was confirmed by quantitative chemical and X-ray fluorescence analysis, as well as by XPS analysis. X-ray absorption spectroscopy indicated that the oxidation state of the adsorbed Co (from either Co(III) or Co(II) complexes) from aqueous pH = 12 electrolytes was Co(II). Extended X-ray absorption fine structure (EXAFS) spectroscopy at 298 K in contact with aqueous 0.010 M KOH indicated that the Co had (6 ± 1) O or N scatterers at (2.08 ± 0.05) Å and (7 ± 1) Co (or possibly Ga or As) scatterers at (3.13 ± 0.05) Å. EXAFS and XPS methods also indicated that exposure of the Co-GaAs surfaces to 1.0 M KOH-0.8 M Se2--0.1 M Se22- for photoelectrochemical measurements yielded a new Co surface phase, with an approximate composition of CoSe1.8.

UR - http://www.scopus.com/inward/record.url?scp=0011592152&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0011592152&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0011592152

VL - 112

SP - 5123

EP - 5136

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 13

ER -