  Through a simulation-based study we develop a statistical model-based
quantification method for atomic resolution first moment scanning transmission
electron microscopy (STEM) images. This method uses the uniformly weighted
least squares estimator to determine the unknown structure parameters of the
images and to isolate contributions from individual atomic columns. In this
way, a quantification of the projected potential per atomic column is achieved.
Since the integrated projected potential of an atomic column scales linearly
with the number of atoms it contains, it can serve as a basis for atom
counting. The performance of atom counting from first moment STEM imaging is
compared to that from traditional HAADF STEM in the presence of noise. Through
this comparison, we demonstrate the advantage of first moment STEM images to
attain more precise atom counts. Finally, we compare the integrated intensities
extracted from first-moment images of a wedge-shaped sample to those values
from the bulk crystal. The excellent agreement found between these values
proves the robustness of using bulk crystal simulations as a reference library.
This enables atom counting for samples with different shapes by comparison with
these library values.
