The oxidation of membrane lipids by reactive Oxygen Species, ROS, is implicated in cell apoptosis, cancer and ageing. We have performed preliminary experiments studying the degradation of a 1H-DPPC lipid bilayer at the solid water interface initiated by a single ROS species - singlet oxygen. The bilayer was deposited on a silica substrate and singlet oxygen was produced by mixing hypochlorite ions, ClO-, with hydrogen peroxide in situ. A rapid, quantifiable amount of DPPC was lost from the interface, followed in real time by neutron reflection. The experiments worked extremely well and in this continuation proposal we wish to study tail and head deuterated DPPC so that we can clearly see the lipid "head" and lipid "tail" regions and follow the relative kinetics of attack, thus providing a complete set of data for final analysis and publication.