Contains reports on two research projects.Joint Services Electronics Program (Contract DAAG29-78-C-0020

McClellan, Michael R.

McFeely, F. Read

Sayers, Michael J.

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IV. PHOTOEMISSION SPECTROSCOPYAcademic Research StaffProf. F. Read McFeelyGraduate StudentsMichael R. McClellan Neal D. ShinnMichael J. Sayers Michael Trenary1. ANGLE-RESOLVED PHOTOEMISSION SPECTROSCOPYJoint Services Electronics Program (Contract DAAG29-78-C-0020)F. Read McFeely, Michael R. McClellan, Michael J. SayersDuring the past few years we have been working to develop a highly sensitive ver-satile instrument to perform electron-spectroscopic experiments on surf ces. Thiswork has been substantially completed. The instrument we have constructed is basedaround a 180-degree spherical-sector electrostatic electron-energy analyzer capableof rotating 360 degrees in a horizontal plane and 100 degrees in a vertical plane, thusenabling us to perform angle-resolved electron-spectroscopic measurements of alltypes. In addition, the incorporation of an efficient input lens system provides us witha very large accessible range of electron energies we can analyze with high transmis-sion, thus allowing us to use the same energy analyzer in conjunction with excitationsources ranging from 2 keV down to 1 eV.Our primary experimental effort in the coming year will be to use this system tostudy the orientational effect of the surface upon adsorbed molecules via angle-resolvedultraviolet photoemission spectroscopy. In order to perform these experiments in anoptimum fashion polarized photons are required. In the past year we have built andtested a rotatable UV polarizer which has given us roughly 50%7 of theoretical intensityfor HeII photons generated in a discharge lamp. The use of a multichannel electrondetector (currently installed in the system and being tested) will provide for us theincreased sensitivity necessary to do these experiments with the reduced polarizedphoton flux.2. ELECTRON-ENERGY LOSS SPECTROSCOPYJoint Services Electronics Program (Contract DAAG29-78-C-0020)F. Read McFeely, Michael R. McClellan, Michael J. SayersIn addition to the completion of our energy-analysis system, we have also designedand constructed an electron monochromator, for performing high-resolution electron-PR No. 121(IV. PHOTOEMISSION SPECTROSCOPY)energy loss experiments. These experiments will allow us to elucidate the vibrationalproperties of the molecules of the surface. We will be able to perform these experi-ments simultaneously with the angle-resolved photoemission experiments. At thepresent time this monochromator can produce a beam of usable intensity with approxi-mately thirty-meV resolution. While we plan on a substantial effort to improve thisto approximately 10 meV in the coming year, this beam is already useful for studyinghigher frequency vibrations, and, in particular, the study of large-momentum transferscattering.PR No. 121

Photoemission Spectroscopy

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Photoemission Spectroscopy

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