HREELS STUDY ON COADSORPTION OF OXYGEN AND CYCLOHEXANONE ON THE PT(111) SURFACE

The coadsorption of cyclohexanone and oxygen on Pt(lll) has been inves tigated by HREELS and TDS. At 205 K the presence of oxygen induces an ''extra'' red-shift of the C = O stretching of coadsorbed cyclohexanon e. Heating this coadsorbed surface from 205 to 250 K leads to further dehydrogenation to form intermediate species and to complete disappear ance of the C = O stretching band. Above 300 K, the molecule rings of dehydrogenation species cleave to form hydrocarbon fragments and CO mo lecules which directly desorb into the vacuum or react with preadsorbe d oxygen to produce CO2 which leave the surface immediately. TDS resul ts provide further evidence that the preadsorbed oxygen promotes the d ecomposition of cyclohexanone.