If we are able to see the emission spectra from the hydrogen Balmer series. It should give interesting access to the processes going on in the cell.
If certain emission lines are suppressed for example it might imply that those transitions are forbidden for some reason or if the transmission bellow a certain energy is blocked by the electron plasma frequency for example.
slight shifts in spectra might indicate heavier nuclei or isotopes
Spectral line broadening might indicate high velocities and temperatures or maybe more exotic processes where athe state of the atom or nucleus is in transition. What would be the effect on these spectra if a H- ion was captured and moved towards inner orbitals for example?
Line splitting during EM stimulation may be interesting if it occurs
i wonder if any emission spectra from Helium is seen this could be very good proof of LENR process if it occurs.
Are visible spectral emissions from the lithium or nickel or tungsten also seen?
i wonder if we had a broad spectrum light source behind the cell if we would see any absorption lines or broad spectra effects as well.