HREELS oxidation

S.W. Jorgensen, N.D.S. Canning, and R.J. Madix, A HREELS, TPD study of nitric oxide adsorption, desorption and reaction on clean and sulfur covered palladium (100), Surf. Sci. 179, 322-350 (1987). 

Ammonia oxidation was a prototype system, but subsequently a number of other oxidation reactions were investigated by surface spectroscopies and high-resolution electron energy loss spectroscopy XPS and HREELS. In the case of ammonia oxidation at a Cu(110) surface, the reaction was studied under experimental conditions which simulated a catalytic reaction, albeit at low... 

Figure 2.5 Dynamics of oxygen chemisorption at Cu(110) and Mg(0001) surfaces based on XPS and HREELS leading to oxidation of ammonia and imide chemisorbed species. The reactive oxygen is a transient state Cr(s). With ammonia-rich mixture Pathway 2 is dominant whereas for oxygen-rich mixtures Pathway 1 dominates at 295 K.

Spectroscopic studies (XPS and HREELS) established first in 1980 that the activity of oxygen states in the oxidation of ammonia at copper-O surfaces was... 

Simultaneously with the STM studies, Kulkarni et al,14 in Cardiff studied by XPS and HREELS the interaction of ammonia with Ni(l 10)-O and Ni(100)-0 surfaces. There was evidence in the N(ls) spectra for more than one nitrogen state present including N(a), but differentiating between NH(a) and NH2(a) was not possible. The intensity in the N(ls) spectrum region was broad over the range 397-400 eV. As the oxygen coverage increased to >0.3, the oxide O2 component became more prominent and the activity for ammonia oxidation decreased, as was observed by STM. Similar conclusions were reached for water interaction with the Ni(110)-O system.15... 

Figure 10.13 (A) HREEL and (B) Auger electron spectroscopy (AES) spectra for 1.5 monolayer (ML) TO on the Si02(ML)/Mo(112) surface following annealing at various temperatures (a) Si02(ML)/Mo(112), (b) oxidized at 600 K, (c) oxidized at 800 K, (d) annealed at 1200 K, (e) annealed at 1400 K, and (f) 1 ML Ti oxidized at 800 K. (From Chen, M.-S. et al., Surf. Sci., 581, L115-L121,2005. Used with permission from Elsevier Scientific Publishers.)...

The (8X2)-TiOr film can also be synthesized by the stepwise direct deposition of Ti onto an oxygen-covered Mo(112) surface followed by subsequent oxidation-annealing cycles. However, the quality and reproducibility are not comparable with growth on the SiOz film. In either case, analysis of the HREELS and XPS results indicate that the oxidation state of the Ti is probably +3. This reduced Ti state is apparently responsible for the ability of Au and other metals to wet the surface. 

Sanchez, V. M. and Hiskey, J. B., 1988. Electrochemical study of the surface oxidation of arsenopyrite in alkaline media. Metallurgical Transactions B, 19(6) 943 - 949 Sanchez, V. M. and Hiskey, J. B., 1991. Electrochemical behavior of arsenopyrite in alkaline media. Minerals Metallurgical Processing, 8(1) 1-6 Sasaki Takehiko, Goto Yoshio, Tero Ryugo, Fukui Ken-ichi, Iwasawa Yasuhiro, 2002. Oxygen adsorption states on Mo(l 12) surface studied by HREELS. Surface Science, (502 - 503) 136-143... 

Adsorption of both CO and NO on nonpolar CoO(OOl) and polar CoO (111) epitaxial films has been investigated by Schonnenbeck et al. (289) with HREELS and NEXAFS. Comparison with results for NiO(OOl) and NiO(lll) surfaces was also reported. On all these oxide surfaces, NO exhibited stretching frequencies that were red shifted, whereas the v(CO) band is very close to that of the free molecule. 

Therefore, HREELS is capable, like SIMS, of disclosing molecular, long-range information on the polymer surface. However, at this stage, it is fair enough to address our ignorance of the influence of the substrate on the vibrational response of a polymer thin film What are the effects of substrate quality - pure metal or with native oxide -, roughness on the atomic scale, and polarizability Authors (8.11) do feel these external parameters must be controlled and taken into account. 

In an early HREELS study of Cr deposition onto polyimide (2b.81. bonding interactions of the Cr atom affecting the carbonyl stretching vibrations were clearly evident. In a further attempt to gain more details on the chemistry developing at the metal-polymer interface, another preliminary set of spectra was recently collected during the metallization of a polyimide film deposited directly onto a silicon wafer (with its native oxide) (Fig. 7). 

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