The use of nonthermal activation methods, particularly low-energy electrons, to prepare spectroscopically significant amounts of adsorbed hydrocarbon fragments on transition metal surfaces is reviewed. Generally, a weakly adsorbed molecule is exposed to a controlled fluence of low energy, less than or equal to 50 eV, electrons. Through impact ionization or resonant attachment, the neutral adsorbate becomes a short-lived ion and, during its lifetime, a C-H bond is activated and dissociates, providing the hydrocarbon fragment of interest. Once the alkyl fragment is formed, its transient kinetics, with and without coadsorbed species, can be investigated through thermal processing. In this paper, phenyl and vinyl groups on Ag(111) and methyl groups on Pt(111) are discussed.