High-resolution electron energy loss intermediates

With the stability of this intermediate established, its spectral features in photoemission and high resolution electron energy loss (vibrational) spectroscopy (EELS) could be determined. Indeed, with ultraviolet photoelectron spectra (UPS) it was shown that methanol reacted with the preadsorbed oxygen to... 

The preference of Eq. (21a) for C02 dissociation may be well anticipated. It has been shown [see, for example, the high-resolution electron energy loss spectroscopy (HREELS) studies of C02 on Re(001) (71a), ultraviolet/ X-ray photoelectron spectroscopy (UPS/XPS) studies of C02 on Fe(lll) and Fe(l 10) (37), and computer simulations for C02 on Pt(l 11) (71b)] that the molecule is practically undistorted (symmetric and linear) in the ground chemisorbed state but strongly distorted (nonsymmetric and bent) as an intermediate preceding the dissociation C02 s — COs + Os. So, there is a good reason to believe that in the transition state the coordinated C—O bond is strongly expanded [by 0.12 A (71b)] and becomes very weak. But the weaker the C—O bond (xc0 — 0), the more accurate is Eq. (21a). 

In contrast to the acetaldehyde decarbonylation, reactions with ethanol over Rh (111) did not lead to formation of methane but rather to an oxametallocycle via methyl hydrogen abstraction. These data suggest that ethanol formed over supported rhodium catalysts may not be due to hydrogenation of acetaldehyde. This study shows how surface science studies of model catalysts and surfaces can be used to extract information about reaction mechanisms since the nature of surface intermediates can often be identified by methods such as temperature programmed desorption and high resolution electron energy loss spectroscopy. 

Qiu H, Idriss H, Wang Y, Woll C (2008) Carbon-carbon bond formation on model titanium oxide surfaces identification of surface reaction intermediates by high-resolution electron energy loss spectroscopy. J Phys Chem C 112 9828... 

Madix RJ, Gland JL, Mitchell GE, Sexton BA (1983) Identification of the intermediates in the dehydration of formic-acid on Ni(llO) by high-resolution electron-energy loss vibrational spectroscopy. Surf Sci 125 481... 

---