The atomic-resolution spatial analysis capability of scanning tunneling microscopy is combined with the chemical analysis capability of Fourier transform infrared spectrometry as an integrated approach for atomic scale chemical identification, This approach was tested by studying the adsorption and decomposition of diborane (B2H6) on Si(001). Diborane interacts with Si(001) to produce a metastable B2H5 species, which decomposes into stable surface BH2 units. They further decompose at elevated temperatures; the hydrogen produced can be liberated either onto the surface or into the gas phase, depending on the availability of free Si surface sites,