 In addition, she discovered that electron energy loss spectroscopy can be used to detect species absorbed in the bulk of a substrate, and can be used to differentiate between bulk and surface species.This paved the way for her discovery that hydrogen atoms absorbed in the bulk of a nickel sample are the key reactant in the hydrogenation of unsaturated hydrocarbons.Another major discovery involved the reaction of fluorine molecules with a silicon surface (a reaction that is key to semiconductor device etching), in which the silicon surface abstracts a fluorine atom from the incident fluorine molecule, and the remaining fluorine atom scatters into the gas phase.