Metal overlayers on organic functional groups of self-assembled monolayers. VI. X-ray photoelectron spectroscopy of Cr/COOH on 16-mercaptohexadecanoic acid
- National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)
The interaction of Cr with the COOH groups of a self-assembled monolayer (SAM) of 16-mercaptohexadecanoic acid [HS(CH{sub 2}){sub 15}COOH] on gold was studied by x-ray photoelectron spectroscopy (XPS). For each Cr overlayer thickness, a {ital freshly} {ital prepared} SAM was exposed to the evaporative deposition of Cr at {le}1{times}10{sup {minus}8} Torr and then transferred immediately {ital in} {ital situ} to a surface analysis chamber held at {le}5{times}10{sup {minus}10} Torr. Metallic Cr is deposited as evidenced by a Cr 2{ital p}{sub 3/2}--2{ital p}{sub 1/2} splitting of 9.2 eV for 1 nm thick Cr films on Au. The C 1{ital s} and O 1{ital s} binding energies and intensities for the initial COOH-terminated SAM are consistent with the presence of the O=C---OH end group at the surface. For Cr overlayers of 0.04--1 nm average thickness, we identify Cr--COOH interactions primarily by changes in the O 1{ital s} level. For 0.04 nm Cr/COOH, the O 1{ital s} peak is narrowed and fitted by a single component at 532.9 eV that is between the O---C (533.9 eV) and O=C (532.5 eV) components of the bare SAM. The narrow width of this peak is evidence that the two oxygens of a single COOH end group interacting with Cr are indistinguishable by our instrument. For 0.07--1 nm average overlayer thickness, a low binding energy component (531.0--530.3 eV), assigned to a Cr(III) oxide, is of gradually increasing intensity. For coverages below 0.6 nm, analysis of XPS peak intensities indicates that adsorption of an adventitious oxygen-containing species has little effect on the results. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}
- Research Organization:
- National Renewable Energy Laboratory
- DOE Contract Number:
- AC36-83CH10093
- OSTI ID:
- 64952
- Journal Information:
- Journal of Vacuum Science and Technology, A, Journal Name: Journal of Vacuum Science and Technology, A Journal Issue: 3 Vol. 13; ISSN JVTAD6; ISSN 0734-2101
- Country of Publication:
- United States
- Language:
- English
Similar Records
Simulation and Modeling of Self-Assembled Monolayers of Carboxylic Acid Thiols on Flat and Nanoparticle Gold Surfaces
X-ray photoelectron spectroscopy analysis of the copper/arachidic acid organized molecular assembly interface: Charging phenomena