This technique is based on the ESD technique, except that the direction of the ions emitted from the surface are also recorded. This can provide information on the direction of the bonding of the molecule to the surface. Other data available with the technique include Inter-molecular forces, bonding length and thermal dynamics. Low energy electrons are directed at the surface and interact with an absorbate molecule which may be excited to an ionised or excited state. The molecule may then be ejected from the surface.