Controlling CH 2 dissociation on Ru(0001) through surface site blocking by adsorbed hydrogen

Experimental Characterization of CCH(ads) and CCH2(ads) during the Thermal Decomposition of Methane and Ethylene on Ru(0 0 0 1)

“…In experiments in which the surface temperature was set to 300 K or lower it was necessary to increase the nozzle temperature to 930 K to get significant adsorption . Nozzle temperatures of 860 and 930 K result in a kinetic energy per CH 4 molecule of ≈0.6 and 0.8 eV, respectively . In agreement with previous work, it was found that dosing methane molecules with such enhanced kinetic energy on Ru(0 0 0 1) increases the sticking coefficient by several orders of magnitude at low surface temperatures ,.…”

“…Details of the temperature control and sample preparation have been described previously . In brief, before each measurement the Ru(0 0 0 1) crystal was cleaned by 20 min Ar + ‐sputtering (sputter current ≈5 μA), then baked for 10 min at 1260 K with a 10 −7 mbar oxygen background pressure, and finally heated to 1510 K (to remove remaining surface oxygen).…”

“…This process was repeated until no more CO desorbed from a given sample. The detected CO signal was calibrated by using a CO monolayer, thus allowing quantification of the initial carbon coverage (see for details).…”

“…With the exception of one study by us, previous work exploring CH 4 decomposition on Ru(0 0 0 1) has investigated samples prepared at surface temperatures above 350 K to overcome the unfavorable temperature‐dependent sticking coefficient of methane . One plausible explanation for the inability to identify intermediates that appear early in the dissociation process [e.g.…”

“…Herein, we fill these gaps by characterization of the CH stretch spectral response with <5 cm −1 resolution during the thermal decomposition of C 2 H 4 and CH 4 adsorbed on Ru(0 0 0 1). Although both samples are prepared in situ, in contrast to most prior work, we employ a supersonic molecular beam source to dose CH 4 , thus allowing dosing at significantly lower surface temperatures than previously reported (see our previous study for details). By concurrently characterizing both C 2 H 4 and CH 4 decomposition we unambiguously resolve the presence and temperature stability of a number of CH‐containing intermediates (i.e.…”