Field ionization 10-Φ。 X。= The gas atoms are eventually Xc eF accommodated at crystal ledge He4.4×1010V/m and terrace sites before being Ne3.7×1010V/m ionised and field evaporated off H22.3×1010V/m the surface. a FIM image of Rhodium imaged in 20K/70 kV by Helium gasField ionization eF I x e c −  = 0 He 4.4 ×1010 V/m Ne 3.7 ×1010 V/m H2 2.3 ×1010 V/m FIM image of Rhodium imaged in 20K/70 kV by Helium gas 6 The gas atoms are eventually accommodated at crystal ledge and terrace sites before being ionised and field evaporated off the surface