Electron density waves in a quantum corral.

[Pickers]

Originally Posted by Del Lardo

Assuming hydrogen atoms then you would be looking at ~1.5^18 atoms in the photo give or take a few trillion

[pedant] The number of sig-fig in your assumption does not lend itself to an uncertainty on the scale of trillion (10^12). Unless of course, you are using long scale numerical system (in which a trillion is 10^18), in which case your estimation is too accurate given that you suggested a level of accuracy to the nearest 0.1x10^18 by denoting it to 1 decimal place.
[/pedant]