Adsorption of NH$_{3}$ on Si(001) and Bi nanolines

Ammonia adsorbs dissociatively onto the Si(001) surface. Using scanning tunnelling microscopy(STM), we have identified the major and minor fragments that result and have found that adsorption is correlated along dimer rows. From our STM data we have determined the strength of the correlation between neighbouring adsorbates, and found that the direction of the correlation changes between 300K and 450K. We propose a reaction pathway based on the STM data and DFT modelling. The Bi nanoline is inert to adsorption of ammonia, and hence ammonia can be used to passivate the Si(001) surface.