I'm not quite sure what you are asking. Atomic nitrogen would exhibit a mass peak at  14 Da while molecular nitrogen would have a mass peak of 28 Da (ignoring isotopes). Although the nitrogen triple bond is extremely strong, I don't know the probability that the MS could create atomic nitrogen when placing a charge on the molecule, and maybe that is your question.

I could be wrong, but I suspect atomic nitrogen would not be very abundant unless it is being created by light or another reactive species, and maybe that is what you are trying to measure. I suspect it would be very short-lived.

Thank you Jack, that basically answers my question. I'm trying to crack molecular nitrogen into atomic species, and was just wondering if we would be able to see that in Mass Spec. 

The short answer is no. Atomic N is formed in the EI source of your RGA; you cannot distinguish between what is formed by the EI process and what might be present in your reactor