The adsorption of 1,3 disilabutane on Si(100)-(2x1) is studied both computationally and experimentally. First, the possible adsorption species are calculated through density functional theory using the Becke three parameter Lee-Yang-Parr functional. The Si9H12 cluster is adopted to simulate the Si(100) dimer. Frequency calculations are also performed to find the harmonic frequencies and infrared intensities of the calculated species. Adsorption experiments are then performed on the Si(100)-(2x1) surface. The surface is subsequently characterized using high-resolution electron energy loss spectroscopy. By comparing calculated and experimental spectra, it is found that the most probable adsorption product is the C2H9Si2 species bonded to the surface through a silicon-silicon bond. To confirm this finding, the transition state of this reaction is calculated and compared with other possible adsorption paths. It is found that the chemisorption reaction leading to silicon-silicon bonded C2H9Si2 is the most probable reaction with an activation energy of about 11 kcal/mol. (C) 2003 American Institute of Physics.