Tip Improvement And Spectroscopic Research Based On The Scanning Probe Electron Energy Spectrometer

Nowadays,surface science has been developed into a frontier cross-disciplinary subject which covers a wide range of topics and the development of scanning tunnel-ing microscope(STM)has played a significant role in promoting its progresses.Al-though STM can enable us to directly obtain the surface nanoscale topography,it can-not distinguish different chemical elements.Thus when we are studying more and more complicate surface systems,using STM cannot provide us comprehensive physical and chemical information.In order to solve this problem,scanning probe electron energy spectroscopy(SPEES)has been developed in recent years as a novel in situ analysis technique.This technique uses electrons emitted by the STM tip to detect the surface electronic states.It can also work in the regular STM model thereby realizing simulta-neous measurements of surface topography and related electronic properties.This tech-nique can enable us to detect the specific nanoparticle's electronic states with the local electron beam.Apart from this,SPEES can also be able to achieve the spectroscopic imaging with spatial resolution based on the specific energy-loss signal.Therefore,the progress of SPEES will be of great importance for us to understand the properties of various nanoparticles on surface.This thesis is based on our home-made SPEES apparatus,conducting near-field spectroscopic research about the silver nanoparticles,surface plasmon and trying to im-prove the present probe in order to further improve the spectroscopic spatial resolution of the SPEES.This dissertation composes of 3 chapters.In the first chapter,we intro-duce the general principle of the SPEES including the STM technique,field emission effect and electron energy spectroscopy.Upon this we present the recent development of the near-field electron energy spectroscopic imaging contributed by several interna-tional groups and our group's recent achievements in this field.In the second chapter,the overall structure of the new SPEES apparatus is discussed which consists of the STM module,analysis and detection modules,etc.The preparations for the STM tips and sil-ver samples are also described.At last,we introduce our latest spectroscopic research based on this apparatus.In the chapter 3,we introduce the technological processes for microelectrode-shielding tips in detail which aim to improve the probe's performance in the SPEES experiment.Through the SIMION simulation and spectroscopic exper-iments about the advantages of this novel tip in detection efficiency,we confirm that with this ME tip electron energy spectra can be measured at a much closer tip-sample distance than before.This indicates that this type of novel tip is available for SPEES ex-periment,which will improve the spectroscopic spatial resolution of SPEES technique in the future.