John J. Barton

Physics, IBM T. J. Watson, 1986-1991

While in the Physical Sciences Department at IBM's TJ Watson Reseach Center I worked on the theory and experiment for Photoelectron Holography. This is a technique for determining the atomic structure of surfaces using internally generated spherical electron waves. As shown here, the incoming xray excites core-level photoelectron waves. Part of the wave (the object wave) goes directly into the electron detector. Other parts of the wave travel in to the crystal where they can be scattered into the detector. Interference between the object and scattered waves gives the photoelectron hologram. The holograms can be inverted to give images of the crystal structure. Moreover, "Removing multiple scattering and twin images from holographic images" describes a way to remove the holographic twin image by phased summation of holograms. It might be applied to photoelectron holograms as illustrated in Fig.1 and Fig 2 from the paper. (This paper was published in Phys. Rev. Lett., 67:3106, 1991).

• And if I really dig back in time I can remember a PhD in Chemistry from UC Berkeley, a Master in Applied Physics from Calif. Institute of Technology. Yes, we did have computers then ;-).