Adsorption and Reaction Mechanisms of Thiophene over Sulfided Ruthenium Catalysts

1987 ◽  
Vol 111 ◽  
Author(s):  
Ray A. Cocco ◽  
Bruce J. Tatarchuk
Keyword(s):  
Binding Energy ◽  
Mass Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Reaction Mechanisms ◽  
Temperature Programmed Desorption ◽  
Ruthenium Catalysts ◽  
Subsequent Annealing ◽  
X Ray ◽  
Temperature Programmed ◽  
Secondary Ion

AbstractAdjustable (hydrogenolysis/hydrogenation) ratios (i.e., selectivity) of thiophene over sulfided ruthenium catalysts have been observed to depend on the method of presulfidization. Sulfidization in 10% H2S/H2 at 300–800K yielded a selectivity greater than 100, whereas a ratio of ca. 1 was noted after presulfidization in 100% H2S. The transition from one selectivity regime to another is reversible and can be changed via subsequent annealing or resulfidization procedures. X-Ray photoelectron spectroscopy shows similar results where sulfidization in 100% H2S yields: (i) a higher sulfur uptake with a corresponding 0.5 eV shift of the S 2P1/2–3/2 peaks to higher binding energy; (ii) multilayer sulfur incorporation at lower temperatures; and (iii) similar reversible behavior following subsequent annealing or resulfidization. Secondary ion mass spectroscopy and temperature programmed desorption studies also reveal that sulfur coverages affect thiophene adsorption, orientation and cracking on ruthenium surfaces.

Interactions of Ge Atoms with High- ê Oxide Dielectric Surfaces

2005 ◽  
Vol 879 ◽  
Author(s):  
Scott K. Stanley ◽  
John G. Ekerdt
Keyword(s):  
Oxide Layer ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Temperature Programmed Desorption ◽  
Tungsten Filament ◽  
X Ray ◽  
Dielectric Surfaces ◽  
Temperature Programmed ◽  
The Stability ◽  
Ge Nanocrystals

AbstractGe is deposited on HfO2 surfaces by chemical vapor deposition (CVD) with GeH4. 0.7-1.0 ML GeHx (x = 0-3) is deposited by thermally cracking GeH4 on a hot tungsten filament. Ge oxidation and bonding are studied at 300-1000 K with X-ray photoelectron spectroscopy (XPS). Ge, GeH, GeO, and GeO2 desorption are measured with temperature programmed desorption (TPD) at 400-1000 K. Ge initially reacts with the dielectric forming an oxide layer followed by Ge deposition and formation of nanocrystals in CVD at 870 K. 0.7-1.0 ML GeHx deposited by cracking rapidly forms a contacting oxide layer on HfO2 that is stable from 300-800 K. Ge is fully removed from the HfO2 surface after annealing to 1000 K. These results help explain the stability of Ge nanocrystals in contact with HfO2.

scholarly journals Phosphorus Behavior in Heavily Phosphorus-Doped Silicon Surfaces due to Annealing. X-Ray Photoelectron Spectroscopy and Secondary Ion Mass Spectroscopy.

Shinku ◽  
1995 ◽  
Vol 38 (3) ◽  
pp. 295-298 ◽  
Author(s):  
Wen Biao YING ◽  
Yusuke MIZOKAWA ◽  
Yoshitomo KAMIURA ◽  
Yong Bing YU ◽  
Masafumi NISHIMATSU ◽  
...  
Keyword(s):  
Mass Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Silicon Surfaces ◽  
Secondary Ion Mass Spectroscopy ◽  
X Ray ◽  
Doped Silicon ◽  
Phosphorus Doped ◽  
Secondary Ion

The Sodium Loss and Transport through the Walls of the Ceramic Discharge Tube of High Pressure Sodium Lamps

2006 ◽  
Vol 514-516 ◽  
pp. 1363-1368 ◽  
Author(s):  
Henriett Lovas ◽  
Vargane Katalin Josépovits ◽  
Zoltán Tóth ◽  
János Madarász
Keyword(s):  
High Pressure ◽  
Mass Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Glass Surface ◽  
Oxide Ceramic ◽  
Internal Wall ◽  
Dissociative Mechanism ◽  
X Ray ◽  
Sodium Loss ◽  
Secondary Ion

In this work we present the investigations on the blackening of the outer jacket of the High Pressure Sodium (HPS) lamps. For this purpose ceramic arc tubes and their glass outer jackets taken from lamps burned for different times (0h-10000h) were examined by X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectroscopy (SIMS) in order to determine the composition of the deposit on the internal wall of glass outer jacket. In the case of the several thousand hours burned lamps the outer bulb was found to be covered by aluminium, which comes to a black deposit on the glass surface. XPS identified Al on the glass surface can be found in two different chemical state (elemental Al, Al2O3). The assumed evaporation of aluminium-oxide ceramic tube might be described by a dissociative mechanism of the alumina evaporation. This papers described the possible mechanism of the alumina evaporation. Na was also found in the black deposit, whose cause of this in the case of the several thousand hours burned lamps is probably related to the sodium transport through the walls of the arc tube

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