Messenger Spectroscopy Positron LEPD RHEPD Positron work function measurement Positron re-emission spectroscopy and microscopy Re-emitted positron energy loss spectroscopy (REPELS) Positron tunnelling spectroscopy Positron backscattering Ps Ps emission/formation spectroscopies Inverse Ps formation spectroscopy" Ps diffraction* Gamma photon Surface ACAR Positron-annihilation microscopy Electron PAES Positron-induced secondary electron emission
LEPD Positron work function Positron reemission spectroscopy Positron tunneling spectroscopy Positron backs℃attering positrons in positrons out P sitron positronium gamma rays out out emmission Surface spectroscopy positrons irf positrons in ACAR positrons in efectrons out PEAS Positron-induced secondary electrons
7.正电子衍射 低能正电子衍射LEPD 正电子在表面上最成功的应用就是由美国 Brandeis大学的Canter和他的合作者在1980年开 创的低能正电子衍射(Low-Energy Positron Diffraction,LEPD),该研究组经过20多年的发 展，他们已经表明LEPD技术可以获得高质量的结 果，并与理论结果相符合。由于正电子有较大的 非弹截面，因而这使得该技术比之传统的低能电 子衍射(Low-Energy Electron Diffraction, LEED) 技术在研究表面结构上更加灵敏
ℷ⬉ᄤ㸡ᇘ ℷ⬉ᄤ㸼䴶Ϟ᳔៤ࡳⱘᑨ⫼ህᰃ⬅㕢 Brandeis ᄺⱘCanterҪⱘড়㗙1980ᑈᓔ ߯ⱘԢ㛑ℷ⬉ᄤ㸡ᇘ˄Low-Energy Positron Diffraction, LEPD˅ˈ䆹ⷨお㒘㒣䖛20ᑈⱘথ ሩˈҪӀᏆ㒣㸼ᯢLEPDᡔᴃৃҹ㦋ᕫ催䋼䞣ⱘ㒧 ᵰˈᑊϢ⧚䆎㒧ᵰⳌヺড়DŽ⬅Ѣℷ⬉ᄤ᳝䕗ⱘ 䴲ᔍ䴶ˈ㗠䖭Փᕫ䆹ᡔᴃ↨ПӴ㒳ⱘԢ㛑⬉ ᄤ㸡ᇘ˄Low-Energy Electron Diffraction, LEED˅ᡔᴃⷨお㸼䴶㒧ᵘϞࡴ♉ᬣDŽ Ԣ㛑ℷ⬉ᄤ㸡ᇘLEPD
Positron Diffraction Experiments e+ screen e+ sample 入 screen screen sample sample TPD LEPD RHEPD Transmission Low Energy Reflection High Positron Positron Energy Positron Diffraction Diffraction Diffraction 100keV·1MeV 10·500eV 10·100keV Bulk·Study Surface·Study
LEPD Grids Positron Gun Crystal 10-500eV Screen
LEPD Positron Gun 10-500 eV