The surface chemistry of allyl bromide, 1-iodopropane, 1-chloro-3-iodopropane and the electron induced chemistry of cyclopropane adsorbed on Pt(111).

摘要

The electron-induced chemistry of cyclopropane and the thermal chemistry of allyl bromide, 1-iodopropane and 1-chloro-3-iodopropane adsorbed on Pt(111) was studied. The hydrocarbon fragments generated by thermal or electron-induced decomposition of these molecules on the Pt(111) surface are of catalytic interest, and identification and characterization of these hydrocarbon fragments is important.;Allyl bromide adsorbs both molecularly and dissociatively on Pt(111) at 95 K. For coverages below 0.38 monolayers (ML), ;1-Iodopropane adsorbs molecularly at 100 K. With heating n-propyl groups form and react between 160 and 220 K by ;HREELS and x-ray photoelectron spectroscopy (XPS) indicate molecular adsorption of 1-chloro-3-iodopropane on Pt(111) at 100 K. HREELS indicates that some C-I bond cleavage has occurred by 205 K. Upon subsequent C-Cl bond scission, a metallacyclopentane forms and undergoes either ;The 50 eV electron induced chemistry of c-;A comparison of the photochemistry of cyclopropane and methane adsorbed on Pt(111) is made in chapter 6. The cross section for cyclopropane photochemistry was ca. 1 order of magnitude smaller than that of methane. Excitation mechanisms and possibilities for the difference in cross section are discussed.