It appears the article is referring to tholins[1], which are actually molecules containing nitrogen rather than atomic (or even diatomic) nitrogen. Nitrogen at

It appears the article is referring to tholins[1], which are actually molecules containing nitrogen rather than atomic (or even diatomic) nitrogen. Nitrogen atoms themselves are essentially always the same size, except when either a) more neutrons have been added to the core, creating a different isotope of nitrogen (in this case the atom is still very much the same size, just heavier) or b) electrons have been added/removed from the outer shells, creating a chemically differently-behaving ion. [1] https://en.wikipedia.org/wiki/Tholin https://en.wikipedia.org/wiki/Tholin