Intensity calibration and atomic imaging of size-selected Au and Pd clusters in aberration-corrected HAADF-STEM

Abstract

We report an experimental calibration of the exponent α, which relates intensity (I) and atomic number (Z) in HAADF-STEM imaging. The method employs size-selected Au923 and Pd923 clusters in an aberration-corrected 200 kV microscope. We find α = 1.46 ± 0.18 for an inner collection angle of 62 mrad. The value of α is needed in the quantit!ative compositional analysis of, e.g., bimetallic nanostructures. The atomic structures of these two examples of size-selected magic-number clusters are also reported.