Hydrogenation of the atomic carbon deposited on the Pt(111) surface studied by low electron energy loss spectroscopy and thermal desorption mass spectrometry

Abstract

The properties of carbon layer on the Pt(111) surface with submonolayer coverage and its activity towards hydrogen have been studied by low electron energy loss spectroscopy and thermal desorption mass spectrometry. The layer of C(ads) atoms was prepared from a special source which produced a carbon atom flow free of admixtures and clusters. It was shown that after deposition of carbon on Pt(111) at 100 K and with n C ≈ 2 × 10 14 cm -2 the layer was obtained chiefly containing the isolated C(ads) atoms. The high activity of the adsorbed atoms was established; the reaction C(ads) + H(ads) was initiated at 170 K and in the course of reaction CH(ads) was produced. These particles are stable towards dissociation up to 500 K. Interaction of the carbon layer ( n C ≈ 10 15 cm -2 with hydrogen gives rise to the formation of more complex particles and, in particular, ethylidyne ( ▪(ads) identified according to the following vibrational bands: v(CC) at 1130 cm -1 and δ s(CH 3) at 1370 cm -1.