Identify The Pre-experiment Based On Scanning Probe Surface Atoms

Nowadays scanning probe technique has been one of the most importance analytical tools in surface science. It could detect the topography and the electronic structure near the Fermi level of the surface. However the principle of scanning probe technique prevents it form identifying the surface atoms. This thesis focus on two relevant experiments aiming at combining the scanning probe with electron spectroscopy technique to identify the surface atoms: one is to decide the threshold amplitudes of single ultrafast voltage pulses applied to Pt tip which will destroy the graphite surface at a fixed tunneling impedance, the other describes the buildup and adjustment of a toroidal electron energy analyzer(TEEA), which is the key component in the future Scanning Probe Auger Electron Spectrometer (SPAES) of our laboratory.Chapter 1 describes some basic concepts in the identification of surface atoms with scanning probes, the principle of the scanning tunneling microscope and recent progresses in the scanning probe electron spectrometers.In chapter 2, the threshold amplitudes of single ultrafast voltage pulses with different durations that destroy the graphite surfaces at a fixed tip sample distance are systematically investigated by applying single voltage pulses to the Pt tip of a STM. The threshold amplitude V_th vary with the duration of the pulses according to the relationship: V_th = Aarcsinh(B/T_p) . The behavior of the ultrafast pulse through the I/V converter of the STM is also simulated with Laplace transformation method. Based on the experimental data and the simulations, a theoretical model consisting of field evaporation-electromigration-disorder of graphite surfaces is proposed, which could explain the modification process quite well. According to the fitting parameters A, B derived from the experiments and the proposed model, we could estimate the average size of the Pt domains near the STM tips, the Young's module of the graphite under the action of the single pulses and the current density passing through the tunneling junction.We also find that single ultrafast voltage pulse could induce superstructure on the graphite surface, as described in chapter 3. The pulse induced superstructure keep on changing at the beginning, indicating that strong intra-layer strain exist in the pulse induced superstructure. In contrast, another superstructure due to the cleaving process of the graphite is much more stable and will not be destroyed even after single ultrafast pulse applied on it.Chapter 4 describes the key problems which should be resolved in the project of SPAES. It also presents the whole setup of the TEEA and the results obtained after one year's adjustments. With energy resolution of 0.6eV, we measure the L_2,3M_2,3N_2,3 Auger spectrum and the valence electron energy loss spectrum of Ar gas. The M_2,3M_4,5M_4,5 Auger spectrum and energy loss spectrum of Cu jet inlet is also found.