For detailed emissions analysis, including hydrogen emissions, we recommend the Vernier Emissions Spectrometer (VSP-EM).

Hydrogen discharge tubes purchased after January 2012, and with a “revision 1” label on the back side, are filled with a lower pressure of gas. As a result the shorter wavelength emission lines are much more visible than with older tubes.

Older tubes will typically show only weak short wavelength lines, with a very prominent line at 656 nm. The weaker lines can sometimes be seen by overexposing the spectrometer, with the 656 nm line well over scale.