Ethylene on cleaved silicon: High-resolution electron-energy-loss study of an unusual adsorption system in the temperature range 85–300 K

We report on several properties which make the adsorption process of ethylene on cleaved silicon unique with respect to those on all other known substrates. These properties include the independence of the adsorption mechanism of temperature from 85–300 K, the nondissociative character, and the coexistence of π bonding with a strong molecular perturbation. The resulting state does not coincide with any of the known ${\mathrm{C}}_2$ ${\mathrm{H}}_4$ adsorption states, and can be explained by assuming that the 2×1 reconstructed silicon surface is a good π donor.