In brief, quantum particles act like waves sometimes (think ripples of water) and act like particles (think tiny billiard balls) at other times. The consequence of that, and a major tenet of quantum mechanics, is the 'wavefunction' of a quantum particle. A wavefunction of a particle, instead of just being a single point in space, amounts to a probability density of position and momentum.
So now that we know the above, in these images, what they are actually measuring is the spatial probability density of the electrons. The lighter values correspond to high density of electrons. The darker values correspond to less electron density. The high density occurs around the nuclei of the atoms. Thus, atomic resolution. However, note that individual electrons are not resolved in these images.
Finally, I want to recommend against thinking of atoms as electron planets orbiting a nucleus sun full of empty space in between. That thinking ignores quantum mechanics. The truth is much more fascinating, which is that electrons are wave-particles that have probabilistic densities.
P.S. Protons and neutrons are themselves made of up more elementary quantum particles: quarks!
Does the microscope care about probabilistic densities? Aren't these images rendering interference/difference between electrons sent out and electrons received?
Those 'particles' supposedly were in the space and interacted with the electron beams. They were or weren't in a place at a time.
In wave particle-duality, how are we not just suggesting particles are there because it creates an estimate model that helps model behaviors observed?
In the facetted nano-diamond void, why, in the void, do we see apparent 'ghosts' of the lattice in the void? Are there particles there or not? If there are, why are they dim?
Right. Well, given your comment and niels_olson's, I feel I have misspoken about this STEM experiment. Not that was I said about quantum mechanics was wrong, just that its relevance to the measurement in this experiment is misguided.
As niels_olson points out, the primary interaction here is between the electron beam and the atomic nuclei.
While the electrons and nucleus (i.e. protons + neutrons) of atoms are indeed 'particles', they are exhibit wave-particle duality: http://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality
In brief, quantum particles act like waves sometimes (think ripples of water) and act like particles (think tiny billiard balls) at other times. The consequence of that, and a major tenet of quantum mechanics, is the 'wavefunction' of a quantum particle. A wavefunction of a particle, instead of just being a single point in space, amounts to a probability density of position and momentum.
So now that we know the above, in these images, what they are actually measuring is the spatial probability density of the electrons. The lighter values correspond to high density of electrons. The darker values correspond to less electron density. The high density occurs around the nuclei of the atoms. Thus, atomic resolution. However, note that individual electrons are not resolved in these images.
Finally, I want to recommend against thinking of atoms as electron planets orbiting a nucleus sun full of empty space in between. That thinking ignores quantum mechanics. The truth is much more fascinating, which is that electrons are wave-particles that have probabilistic densities.
P.S. Protons and neutrons are themselves made of up more elementary quantum particles: quarks!