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.

The growth of AuGa2 thin films on GaAs(001) to form chemically unreactive interfaces

1986 ◽  
Vol 1 (4) ◽  
pp. 537-542 ◽  
Author(s):  
Jeffrey R. Lince ◽  
Tsai C. Thomas ◽  
Williams R. Stanley
Keyword(s):  
Electron Spectroscopy ◽  
Auger Electron ◽  
Room Temperature ◽  
Substrate Surface ◽  
Film Deposition ◽  
X Ray ◽  
Low Energy Electron Diffraction ◽  
Interface Roughening ◽  
Low Energy Electron ◽  
Electron Energy Loss

Thin AuGa2 films were grown by codeposition from separate Au and Ga evaporation sources on clean GaAs(001) substrates in ultrahigh vacuum, and were studied by Auger electron spectroscopy, electron energy-loss spectroscopy, low-energy electron diffraction, scanning electron microscopy, and x-ray diffractometry. The morphology and crystallinity of the AuGa2 were highly dependent upon the film deposition and annealing history. Films grown on room-temperature substrates were continuous, specular, and polycrystalline, but the dominant orientation was with the (001) planes of the crystallites parallel to the substrate surface. Annealing to temperatures between 300°and 480°C caused the film to break up and coalesce into rectangular crystallites, which were all oriented with (001) parallel to the surface. An anneal to 500°C, which is above the AuGa2 melting point, resulted in the formation of irregular polycrystalline islands of AuGa2 on the GaAs(001) substrate. No interface roughening or chemical reactions between the film and substrate or interface were observed for even the highest-temperature anneals.

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.

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