Investigation of the surface chemistry of crown ethers: the adsorption andreaction of 1,4-dioxane on palladium(111)

1,4-Dioxane adsorbs on Pd(lll) at 80K to form an overlayer saturating at an exposure of similar to 4L (1 L = 1 x 10(-6) Torr s) and desorbs with a pea k centered at similar to 268 K in temperature-programmed desorption. Multil ayer growth commences for exposures >2 L suggesting that they form before t he monolayer is completed. The multilayers desorb at similar to 160 K. Refl ection-absorption infrared spectroscopy of both normal and perdeuterated di oxane suggests that it converts from its usual chair conformation in the ga s phase into a boat conformation in the monolayer, allowing the lone pairs on both oxygen atoms to interact with the surface. A portion of the adsorbe d dioxane thermally decomposes at or below similar to 300 K to desorb ethyl ene and hydrogen and to deposit CO onto the surface. The adsorbed CO therma lly desorbs at similar to 460 K. (C) 2000 Elsevier Science B.V. All rights reserved.