AVS 47th International Symposium
    Surface Science Tuesday Sessions
       Session SS3+MC-TuM

Paper SS3+MC-TuM9
Scanning Probe Energy Loss Spectroscopy: Spectroscopic Analysis of Reflected Electrons in Field Emission STM

Tuesday, October 3, 2000, 11:00 am, Room 210

Session: Technique Innovations: Experiment, Theory and Simulation
Presenter: B.J. Eves, University of Birmingham, UK
Authors: B.J. Eves, University of Birmingham, UK
F. Festy, University of Birmingham, UK
K. Svensson, University of Birmingham, UK
R.E. Palmer, University of Birmingham, UK
Correspondent: Click to Email
Spectroscopic (i.e. chemical) analysis is a key frontier in scanning probe microscopy. We have employed a scanning tunnelling microscope (STM) operating in field emission mode to act as a nanometre scale electron source while the resulting backscattered electrons have been detected with a hemispherical energy analyser. Angular measurements show that the flux of reflected electrons peaks parallel to the surface, consistent with simulations which include the long range field generated by the tip bias voltage. The measured energy loss spectra contain information on the surface and bulk plasmons, and other surface excitations. The Si (111)-7x7 surface was found to show losses at 5, 7.5, 11, 15, and 18 eV. These inelastic losses correspond to an interband transition (5 eV), two surface states (7.5 and 15 eV), and the surface and bulk plasmons (11 and 18 eV, respectively). Spectra have also been measured for a number of different exit angles. With improvements it is believed that the scanning probe energy loss spectrometer (SPELS) can be built to perform electron energy loss spectroscopy with spatial resolution on the scale of 5-50 nm.