This picture was taken in ~1970 at the National Bureau of Standards. I went there to work with Russ Young in the Electron Physics Section on a National Research Council Postdoctorial Fellowship and stayed as a staff member until 1973. The instrument shown is a specially designed defection analyzer (C.E. Kuyatt and E.W. Plummer, Rev. Sci. Inst. 43, 108 (1972).for high resolution field emission energy distribution studies. At NBS I collaborated with Bill Gadzuk to investigate the properties of surfaces using field emission. Key papers (more than 100 citations) originating from this period in my career are listed below.
Field-Emission Studies on Electronic Energy Levels of Adsorbed Atoms, E. W. Plummer and R.D. Young, Phys. Rev. B1, 2008 (1970). Surface States on Tungsten, E.W. Plummer and J.W. Gadzuk, Phys. Rev. Lett. 25, 1493 (1970).
Field Emission Energy Distributions of Hydrogen and Deuterium on the (100) and (110) Planes of Tungsten, E.W. Plummer and A.E. Bell, J. Vac. Sci. and Tech. 9, 583 (1972). Field Emission Energy Distributions, J.W. Gadzuk and E. W. Plummer, Rev. Mod. Phys. 45, 487 (1973).
The second paper was the first experimental observation of surface states on a metal surface.
The paper that was listed as one of the top 100 articles of the 20th century from NIST was:
Resonance Tunneling of Field Emitted Electrons Through Adsorbates on Metal Surfaces, E. W. Plummer, J.W. Gadzuk, and R.D. Young), Solid State Comm. 7, 487 (1969).