> What are the odds of a negative, 100 KeV (medium-high energy) electron in the beam interacting with a heavy, relatively stationary, positively charged nucleus

> What are the odds of a negative, 100 KeV (medium-high energy) electron in the beam interacting with a heavy, relatively stationary, positively charged nucleus? High. > What are the odds of a negative, high energy electron interacting with a low-energy electron that may, occasionally, be in the area? Low. Just to clarify this, so people don't get the wrong idea, electron-electron interactions are also incredibly important in an electron microscope. > and then scan at equal or higher resolution! Note that while this is what's happening here, you can get similar atomic-resolution images without scanning at all, by just illuminating a sample with a broad electron beam (see 'TEM' (or 'conventional TEM') vs 'STEM'). Strictly speaking, STEM and TEM are equivalent techniques (by something called the reciprocity theorem), but in practice you'd almost certainly prefer one over the other depending on your sample and one technique is not necessarily better than the other. > I'm interested in the detector. I'm guessing these are reconstructed using a combination of side-scatter and forward-scatter information. For some of the STEM-HAADF images in the article, a 'high angle annular' (the 'HAA' part) detector is used, which collects electrons that are just scattered at high-angles in the forward direction, because this results in images that are much easier to interpret (intensity is just proportional to mass and thickness). The detector itself is commonly a scintillator/photomultiplier tube combo. There are tonnes of other detectors used though. Until recently, it was common to just expose TEM images onto film (I have some of my own samples actually). An operator would find the region of the specimen they wanted to take an image of using a live view which was the electron beam projector onto a phosphor screen and, when ready, move the screen aside and expose it to film. More recently, the vast majority of TEM micrographs are taken using normal CCD tech.