Chemisorption Geometry, Vibrational Spectra, and Thermal Desorption of Formic Acid on TiO2(110)

1998 ◽  
Vol 05 (01) ◽  
pp. 381-385 ◽  
Author(s):  
S. A. Chambers ◽  
M. A. Henderson ◽  
Y. J. Kim ◽  
S. Thevuthasan
Keyword(s):  
Formic Acid ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
Decomposition Products ◽  
X Ray ◽  
Low Energy Electron Diffraction ◽  
Resolution Electron ◽  
Low Energy Electron ◽  
Temperature Programmed ◽  
Electron Energy Loss

We have used high-energy X-ray photoelectron spectroscopy and diffraction (XPS/XPD), low-energy electron diffraction (LEED), high-resolution electron energy loss spectroscopy (HREELS) and temperature-programmed desorption (TPD) to determine the molecular orientation, long-range order, vibrational frequencies, and desorption temperatures for formic acid and its decomposition products on TiO 2(110). Molecular adsorption occurs at coverages approaching one monolayer, producing a weakly ordered (2 × 1) surface structure. High-energy XPD reveals that the formate binds rigidly in a bidentate fashion through the oxygens to Ti cation rows along the [001] direction with an O–C–O bond angle of 126 ± 4°. During TPD some surface protons and formate anions recombine and desorb as formic acid above 250 K. However, most of the decomposition products follow reaction pathways leading to H 2 O , CO and H 2 CO desorption. Water is formed in TPD below 500 K via the abstraction of lattice oxygen by deposited acid protons.

Adsorption of Oxygen on Sodium Saturated Cu{110}

1986 ◽  
Vol 83 ◽  
Author(s):  
D. E. Grider ◽  
J. F. Wendelken
Keyword(s):  
Photoelectron Spectroscopy ◽  
Low Energy ◽  
Sticking Coefficient ◽  
X Ray ◽  
Low Energy Electron Diffraction ◽  
Metallic Character ◽  
Resolution Electron ◽  
Initial Oxygen ◽  
Low Energy Electron ◽  
Electron Energy Loss

ABSTRACTThe adsorption of oxygen on a sodium saturated Cu{110} surface is examined with x-ray photoelectron spectroscopy (XPS) in an extension of a previous study of this system which utilized low energy electron diffraction (LEED), and high resolution electron energy loss spectroscopy (HREELS). The sodium overlayer, despite the presence of an initial oxide contaminant, shows metallic character. Intentionally adsorbed oxygen is in a different chemical state than the initial oxygen contaminant and causes a reduction in the metallic character of the sodium. The sticking coefficient for oxygen on the sodium saturated surface is almost three times greater than for the bare Cu{11O} surface.

Hydrogen On Semiconductor Surfaces

1998 ◽  
Vol 513 ◽  
Author(s):  
J. A. Schaefer ◽  
T. Balster ◽  
V. Polyakov ◽  
U. Rossow ◽  
S. Sloboshanin ◽  
...  
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Photoelectron Spectroscopy ◽  
Low Energy ◽  
Semiconductor Surfaces ◽  
Hydrogen Passivation ◽  
Low Energy Electron Diffraction ◽  
Resolution Electron ◽  
Low Energy Electron ◽  
Electron Energy Loss

ABSTRACTWe review structural and electronic aspects of the reaction of hydrogen with semiconductor surfaces. Among others, we address the Si(100), GexSi1-x(100), GaAs(100), InP(100), SiC(100), SiC(0001) and SiC(0001) surfaces. It is demonstrated that high resolution electron energy loss spectroscopy (HREELS) in conjunction with a number of other surface sensitive techniques like low energy electron diffraction (LEED) and photoelectron spectroscopy (XPS/UPS) can yield important information about the surface atomic structure, the effects of hydrogen passivation and etching and on electronic properties of the surfaces.

Adsorption and Reaction of TiCl4 on W(100)

1993 ◽  
Vol 334 ◽  
Author(s):  
Wei Chen ◽  
Jeffrey T. Roberts
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Titanium Tetrachloride ◽  
Bound State ◽  
Temperature Programmed Desorption ◽  
X Ray ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Temperature Programmed

AbstractThe adsorption and reaction of titanium tetrachloride (TiC14) on W(100) was investigated using temperature programmed desorption mass spectrometry (TPRS), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and low energy electron diffraction (LEED). TiC14 adsorbs molecularly on W(100) at 100 K. Desorption from the molecularly bound state occurs near 220 K. Competing with desorption is dissociation to adsorbed TiCl3, which reacts to form gaseous TiCl4 near 450 K. TiC13 also decomposes into atomically adsorbed Ti and Cl on the surface upon heating to 700 K.

Formation of a Ba-Te Surface on GaAs

2003 ◽  
Vol 782 ◽  
Author(s):  
Kevin A. Boulais ◽  
Francisco Santiago ◽  
Karen J. Long ◽  
Victor H. Gehman
Keyword(s):  
Electron Diffraction ◽  
Photoelectron Spectroscopy ◽  
Molecular Beam ◽  
High Energy ◽  
Energy Electron ◽  
High Energy Electron ◽  
X Ray ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Polycrystalline Form

ABSTRACTThe formation of a Ba-Te surface on GaAs has been investigated. The surface was created using molecular beam epitaxy (MRS). A GaAs (100) surface was first exposed to Te and characterized using x-ray photoelectron spectroscopy (XPS), reflective high energy electron diffraction (RHEED) and low energy electron diffraction (LEED). The Te-reacted surface was then exposed to BaF2 flux producing a second reaction. In this reaction, the BaF2 dissociated leaving barium on the surface but no fluorine. This is in contrast to the clean (no tellurium) GaAs (100) surface in which BaF2 has been shown to grow single crystal. Although high order exists during early stages of the Ba-Te growth, further exposure gives way to a polycrystalline form. This paper discusses the formation and analysis of the Ba-Te surface.

Effect of Post Exposed Hydrogen on Chemisorbed Ethylene on Si(100)-(2×l)

1993 ◽  
Vol 334 ◽  
Author(s):  
Wolf Widdra ◽  
Chen Huang ◽  
W. Henry Weinberg
Keyword(s):  
Atomic Hydrogen ◽  
Thermal Activation ◽  
Low Energy Electron Diffraction ◽  
Post Exposure ◽  
Resolution Electron ◽  
Low Energy Electron ◽  
Temperature Programmed ◽  
Adsorption Desorption ◽  
Electron Energy Loss ◽  
Molecular Desorption

AbstractThe effect of post adsorbed atomic hydrogen on the adsorption, desorption, and decomposition of ethylene on Si(100)-(2×l) has been studied using high-resolution electron energy loss spectroscopy (HREELS), temperature programmed desorption (TPD), and low-energy electron diffraction (LEED). Exposures to atomic hydrogen of more than 1015 atoms/cm2 convert the initial (2×l) reconstruction of sp3-hybridized, di-σ bonded ethylene to a (l×l) structure. Furthermore, after post exposure to atomic hydrogen, the thermal desorption peak of molecular ethylene is shifted up by approximately 100 K and reduced in intensity. HREEL spectra for deuterated ethylene show the formation of a C-H bond after exposure to atomic hydrogen, whereas the C-C bond remains intact. We explain our data by an atomic hydrogen-driven conversion of the di-σ bonded ethylene to a mono-σ bonded surface ethyl. Thermal activation after post exposure to atomic hydrogen leads to decomposition of about 60% of the initial ethylene in contrast to the observed molecular desorption in the absence of hydrogen.

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