Construction and characterization of the fringe field monochromator for a field emission gun

摘要: Abstract Although some microscopes have shown stabilities sufficient to attain below 0.1 eV spectral resolution in high-resolution electron energy loss spectroscopy, the intrinsic width of high brightness source (0.3–0.6 eV) has been limiting resolution. To lower 50 meV without unnecessary brightness, a monochromator designed consisting short (4 mm) fringe field Wien filter and 150 nm selection slit (nanoslit) both be incorporated gun area microscope. A prototype built tested an ultra-high-vacuum setup (10 −9  mbar). The monochromator, operating on Schottky emission gun, showed stable reproducible operation. nanoslits did not contaminate structure remained stable. By measuring current through direct image beam could attained aligned use Good dispersed imaging conditions were found indicating ultimate 55 meV. Mark II (FFM) was constructed compatible with cold tungsten emitter VG scanning transmission microscope at IBM T.J. Watson research center, New York. 100 kV distribution measured using displayed filtering capability. retarding spectrometer used show 61 meV EELS system FFM is which can This makes it directly applicable for microscopy low-voltage microscopy, where caused by chromatic blur spot.