Cold-neutron depth profiling as a research tool for the study of surface oxides on metalsSpecial Issue on Neutron Scattering in Canada.

A recent experiment at NIST has demonstrated that neutron depth profiling (NDP) based on the (n, α) reaction could be developed into a tool that could be routinely used for the study of passive oxides on metals. Whereas most metals are not (n, α) active, oxides grown with 17O, the only (n, α) active oxygen isotope, can be observed and tracked by this technique. Problems due to contamination of the samples by boron were encountered, but were shown to be surmountable. For our samples, the NDP facility at NIST, as it exists today, has enough flux and energy resolution to separate the α particles emitted by 17O from those emitted by 10B. Substantial improvement in the data collection rate, easily achievable with arrays of additional detectors, will make NDP a useful tool in the study of passive oxides.