Finding the Mystery gas questions

[MonsieurWise]

I'm doing an experiment of the Bohr's theory and the Rydberg constant. I want to find the element of a mystery gas using the derivation of the Bohr's theory:
1/λ=RZ^2 (1/〖n_i〗^2 -1/〖n_f〗^2 )
I think if I have the wavelength lambda, all I need to do is guessing a right series of n_i and n_f till it gets me a straight line.
My problem is I'm not sure that this way can actually work with any gas (Helium for example), or only work with "electron-like" atoms (Singly ionized Helium for example). And I can't find any "Singly ionized Helium spectrum" on the internet. There's only Helium spectrum...
Could someone help me...?
Thank you very much in advance...

 

[Bob S]

The spectral line energies of ionized helium are usually shown as a line of He+ (meaning ionized helium) vs. He (for unionized helium) in tables. The most dominant lines are probably 2p -> 1s (n=2 to n=1) transitions, which are about 4 x 3/4 x 13.6 eV = 40.8 eV (304 Angstroms).

 

[MonsieurWise]

Thanks ^^