Field Calibration Using the Energy Distribution of Field Ionization

Abstract

The accuracy of data obtained by field-ion microscopy is often limited by a ± 15% uncertainty of converting measured voltages into field strengths. Plotting the difference of relative energy deficits of free-space ionized ${\mathrm{H}}_2$, ${\mathrm{D}}_2$, or Kr for sets of two applied voltages against the logarithm of the voltage ratios yields a field factor $k$. The surface field $F_0=\frac{V}{k{r}_t}$ is obtained with the 3% accuracy by which the tip radius $r_t$ can be known. The method is applicable to all metals accessible to field-ion-microscopy.