[en] Helium ion implantation into surfaces can be used to form nanoporous cavity structures with unique features, of interest for applications. The ingress of desired dopant atoms into the material could be enhanced by producing cavity layers that extend to the surface. Ti and Co targets were implanted with He using pulsed plasma-immersion ion implantation (PI^3TM) and monoenergetic accelerator ion implantations. Spatially resolved elemental mapping of C, N and O, using microprobe nuclear reaction analysis was done with a scanned 20 μm diameter deuteron beam. This spatial resolution has enabled several important new results to be obtained. It is demonstrated for the two materials that He implanted surfaces take up more O from the atmosphere than unimplanted surfaces. In Ti, the nanoporous surface exposed by heavy ion damage in a prior heavy ion elastic recoil detection analysis measurement takes up twice as much O and over ten times as much N as the immediately adjacent undisturbed He implanted surface