A Vacuum Generators HB501 field emission scanning transmission electron microscope has been installed and tested. The resolution in bright-field and dark-field has met specifications. It has been possible to image the graphite 3.4 angstrom (0001) lattice fringes and the gold 2.04 angstrom (100) lattice fringes in bright-field. This test necessitated modifications to the microscope room to reduce effects of 60 Hz magnetic fields and shielding of the column to reduce radiofrequency interference. It was possible to demonstrate a current of lnA into a lnm probe diameter required for satisfactory high resolution analytical work. An ultrathin window Tractor Northern x-ray detector was fitted to the STEM column. Its energy resolution was found to be approximately 150 eV at Mn and it produced satisfactory results at low energies. X-ray spectra have been obtained from single molecules of ferritin (containing about 4000 iron atoms): large peak/background ratios were demonstrated confirming that detection limits of a few atoms will be feasible.
