Chemisorption of CO on (1011) titanium studied by XPS, UPS, FDMS, and AIB

Abstract

Chemisorption of CO on the clean (1011) face of a titanium single crystal has been investigated by the techniques of x-ray and uv photoelectron spectroscopy (XPS and UPS), flash desorption mass spectrometry (FDMS), and active ion bombardment (AIB). CO is dissociatively chemisorbed at room temperature to form oxide- and carbidelike species. The (1011) face of Ti is very active; the sticking probability for CO is unity below 0.6 L (1 L = 10 -6 Torr sec) and the surface is saturated at 2 L exposure. Approximately 1% of the chemisorbed CO is desorbed upon heating to 300°C by a mechanism which does not follow simple first-order kinetics. The C and O remaining on the surface at 300°C form titanium carbides and oxides which migrate into the bulk of the crystal between 300 and 500°C. AIB with 500 eV CO+ produces carbides and oxides that are identical to the species on the surface at 300°C. High kinetic energy AIB results in complete dissociation of the CO+ into atoms, thus confirming that chemisorbed CO is dissociated on the (1011) face of Ti. © 1978 American Institute of Physics.