ADSORPTION AND DESORPTION OF CF3I ON RU(001)

We have studied the interaction of CF3I with Ru(001). Adsorption at 100 K is followed by desorption, at higher temperatures, of molecular cf3I, atomic iodine, atomic fluorine, CF2 and CF3 fragments, and a small amount of CF4. The identification of these gases is based on fragmentation patterns, and (in the case of the CF2 and CF3, particles) on the characteristics of accompanying CO. This product distribution indicates that C-I and C-F bonds break. The order of appearance of the dissociative products, with increasing exposure, is: monatomic species < CF2; < CF3 < CF4. We favor a dissociative-site-blocking model to explain this sequential population Finally, CF2 and CF3, desorb at much higher temperatures than polyatomic fragments observed in previous surface studies of halomethanes, suggesting that they are produced by a different mechanism. © 1990.