How does the decay of an atom look like? There is this famous image recorded by IBM using the Scanning tunneling microscope. Those dots are individual Xenon atoms.

I was thinking if it was possible to record the sequence of images of any atom decaying by the same equipment? What is the steps behind decaying? Is it like one moment there is a single atom but the next time we look there is an alpha particle and another atom?
 A: In any image like this, you need to consider what physical interaction led to the measurement information that is displayed. Thinking like this will help you to predict what you might see for any given event. For the example above, of STM imaging of individual atoms, recall that an electrically biased nanoscale tip is scanned above the surface, and at every point the current between the tip and substrate is measured. This tunneling current gives information about the local density of electron states with sub-nanometer resolution. Since the Xenon atoms adsorbed on the surface have a different density of states from the bare substrate, there is a measurable contrast.  If the atoms were instead something radioactive, and underwent a decay event, the question to ask would be: What is the contrast of the atom compared to the decayed particles? My guess is an alpha would fly off the surface into the vacuum, and what would be left would look very similar according to the STM to what was there before.  I could, of course, be wrong, and depending on the details the contrast could be great. But in effect, you would see an increase or decrease in the image contrast. 
Also, keep in mind that a discussion of what happens from one "moment" to the next is all relative: I haven't read the paper, but since STM tends to be a slow, raster scan technique, this image probably took hours to collect. In any case, the frame rate is much, much slower than the timescale of a radioactive decay event.
