Spectroscopic evidence for carbon-carbon bonding in “carbidic” layers on metals

Oxidation of carbidic carbon on a rhodium surface

“…. la) could be observed at low carbon coverages (0c ~< 0.3 ML) [23,30]. This result is partly in contradiction with ref.…”

“…The most commonly used methods of carbon deposition consist of the thermal decomposition of different carbonaceous molecules such as C2H4, CH4, and CO [17][18][19][20], or segregation from the bulk [20]. However, the atomic dispersion of deposited carbon is not well defined due to a high probability of clustering [21][22][23]. The study of a "carbidic" C layer on Ni(100) and Ni(111) made from thermal decomposition of either CO or C2H4 by ultraviolet photoelectrons, C K electron energy loss, and C KVV Auger spectroscopy indicate the presence of C2, and maybe C3 clusters at the surface [23].…”

“…However, the atomic dispersion of deposited carbon is not well defined due to a high probability of clustering [21][22][23]. The study of a "carbidic" C layer on Ni(100) and Ni(111) made from thermal decomposition of either CO or C2H4 by ultraviolet photoelectrons, C K electron energy loss, and C KVV Auger spectroscopy indicate the presence of C2, and maybe C3 clusters at the surface [23]. The minimum coverage of carbon usually deposited by hydrocarbons decomposition is about 0.3-0.5 ML [18].…”

A TEMPERATURE-PROGRAMMED X-RAY PHOTOELECTRON SPECTROSCOPY STUDY OF THE DECOMPOSITION REACTIONS OF UNSATURATED HYDROCARBONS ON Ni(100)

“…All species decompose below 330 K leaving the final decomposition product as carbidic carbon in agreement with literature. [7][8][9]20,21,24 An important conclusion from this analysis is that the thermal chemistry for ethylene decomposition is extremely complex between 150 and 300 K due to the simultaneous evolution and decomposition of several surface intermediates. The resulting mixture of ethylene, vinyl, acetylene, acetylide, methylidyne and carbide, the composition of which is continuously changing, may reasonably account for the inconsistencies in the reaction intermediates reported by previous studies.…”

“…[7][8][9][10][11][12][13][14][16][17][18][19][20][21][22][23][24][25] A central issue addressed in our work concerns the thermal evolution of surface intermediates which clearly reveals the complexity of the decomposition mechanisms involved. In this regard, our re-examination of these systems expands on earlier spectroscopic studies which invariably consist of selected temperature measurements resulting in a diversity of results and a lack of quantitative information on surface intermediate species formed.…”