What are the lowest and highest energetic (electron shell) emission lines considering ANY molecule or atom (observed & theoretical)? I am making this public interactive infographic of the electromagnetic spectrum on the web. In it I visualize all interactions of EM waves with matter. And I try to display boundaries for every interaction.
Emission lines is one of the interactions. But what are the boundaries left and right in the electromagnetic spectrum for these kind of interactions (being electron jumps)?
On the lowest energy level I'lm thinking, it must be close to zero. Which atom or molecule has their electrons in the highest level below valence band so the electrons can jump the smallest gap? Since the higher up the more close they are to eachother.
And for which is the highest jump, since several things influence the size of the biggest possible jumps (like electron density, etc.)
And to make things worse, which ones are the ones that have actually been observed (in nature or lab)? This is a whole other aspect. And I'm wondering if I should even consider taking into account the ones that almost never occur, like below 1%.
And I decided to give myself a headache since I divided them into category "outer electron" and "inner electron" jumps, and molecular and atomic emission lines.
(So in the best case, taking all together, I would love to have 8 answers if possible. But anything that anyone can give is much appreciated of course.)
These are the questions that hold me from finishing my project. I've been searching for years. (Eh, yeah, it's a long term hobby.)
Please help me. Thank you.
 A: The purely-electronic transitions with the highest energy are the K-shell x-rays, produced by vacancies in the electron shell closest to the nucleus. In this database you can search by energy or wavelength. Searching for energies between 100 keV and 1 MeV gives mostly x-rays from the actinides, pooping out below 150 keV. I think (you’ll want to read the associated paper to confirm) that a “KL” x-ray is a $2\to1$ transition, that a “KN” x-ray is a $4\to1$ transition, and that the “K-edge” includes capture to the K-shell from the continuum.
The highest-energy x-rays in the NIST database are the K-edge x-rays from the highest-$Z$ element in the database, $_{100}\rm Fm$. There are several superheavy elements which were unknown or unconfirmed in 2005, when the database was made. It seems like a safe bet that the highest-energy K-edge x-rays from a currently-known element would come from $_{118}\rm Og$. But there have only been five or six oganesson atoms ever detected, and while they probably came into being with K-shell vacancies, they probably produced KL x-rays rather than K-edge x-rays. (The folks who made oganesson weren’t looking at the x-rays anyway.) An interesting homework problem for you would be to compute the energies of x-rays for the heaviest elements.
With the lowest energy, you definitely have a judgement call to make. For one thing, you have the example of the hydrogen Rydberg states, which get arbitrarily close to each other as the principle quantum number gets large. (People talk about the Lyman, Balmer, and Paschen series, where the final state is $n=1,2,3$; the series are named up to $n=6$, and apparently the $n=7$ series has been observed.)
But also your definition of “electron jumps” arbitrarily excludes some interactions.
For example, a hydrogen atom in its ground state can undergo a magnetic dipole (M1) transition in which the electron’s spin flips relative to the proton’s spin; this very slow transition is associated with the astrophysically-important 21cm radio line.
