For detailed emissions analysis, including hydrogen emissions, we recommend the Vernier Emissions Spectrometer (VSP-EM), Go Direct® Emissions Spectrometer (GDX-SPEC-EM), or the Go Direct® Visible Spectrophotometer (GDX-SPEC-VIS).
You may need to adjust the distance between the light source and the tip of the optical fiber or some of the spectrometer settings in order to see distinct peaks at all four wavelengths.
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.