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Field Emission Gun
Scanning Electron Microscope

Hitachi S-900


A Field Emission Gun Scanning Electron Microscope (FEGSEM) of “in‑lens” design capable of 0.8 nm resolution at 30 kV and 3-4 nm resolution at 1 kV.  Magnification ranges from 100 X to 800,000 X.  Electron source is a cold FE gun producing high brightness (109 A / cm2/sr) with little energy spread (<0.2 eV).  Spherical and chromatic aberration coefficients of “objective” lens (final condenser) are Cs = 1.9 mm and Cc = 2.5 mm, respectively.  The “in‑lens” design imposes a sample size limit of ~ 5 mm W X 10 mm L X 2.5 mm H.  Oil-free vacuum systems pump column and sample exchange.  Available image modes include secondary and backscattered electron images.  Two specialized Gatan Model 626 cryostages are available for cryoSEM operation.  Digital images are acquired via an analog‑to‑digital converter / PCI system.


  • Hitachi S-900 with a variety of non-cryo sample holders
  • CryoSEM observation using Gatan Model 626 cryostages
  • Backscatter imaging at TV rates and low voltage (threshold 1.8 kV on gold) with Autrata modified YAG (yttrium aluminum garnet, cerium doped) crystal
  • Keithly Specimen Current Detector


  • High-resolution topographic contrast (Se) and atomic number contrast (BSe) imaging of biological and non-biological samples in both room temperature and cryo modes.
  • Applicable to imaging of immunogold labeled individual cells and bacteria, analysis of semiconductor thin films, etc.


Sample Size, Non-cryo:  ~ 5 mm W X 10 mm L X 2.5 mm H
Sample Size, Cryo:  ~ 3 mm diameter X up to ~2 mm thick