SURFACE-REACTION OF CH2I2 WITH AN AL(111) SURFACE

Reaction between diiodomethane, CH2I2, and an Al(111) surface has been studied by means of surface analytical techniques under ultrahigh vacuum. Thermal desorption experiments revealed that an alkyl-aluminum complex desorbed at 472 K as a dominant desorption species from the surface adsorbed by CH2I2 to a coverage of less than 1 monolayer (ML). On the contrary, desorption of ethylene, physisorbed CH2I2, and aluminum iodide began to be observed above 1 ML at 150 K and 190 K and around 380 K, respectively. The desorption of ethylene was accompanied by the desorption of aluminum iodide. Ethylene is produced on an alkylaluminum surface compound formed on the surface by the reaction between CH2I2 and Al. These reactions on Al(111) are discussed in relation to a similarity with the Simmons-Smith reaction.