My degree was in Electrical Engineering, and as a result I don't fully understand the formatting of the ${}^4S_{3/2}$ ${}^2D_{3/2}$ and ${}^2P_{1/2}$ of the different 2p orbitals, and I don't believe this is the proper forum for learning something undoubtedly more complex than my basic knowledge. I do however know some basics, such as the selection rule that says you cannot transition between orbitals that have the same quantum l number. So my question is the following:
How does Nitrogen transition between these three 2p orbitals? Or are the higher energy states naturally occurring? If so how, don't atoms strive to be in the ground state? Can the transition be forced somehow, such as photon absorption or electron collision to move to the left, or a photon emission to move to the right; perhaps using stimulated emission?
I feel like there are so many more questions worth asking and perhaps these cannot be answered without asking them, but this is my starting point.
Related Link: http://hyperphysics.phy-astr.gsu.edu/hbase/atomic/nitrogenlev.html#c1