Emission spectrum of the H₂ discharge VUV lamp between 110 and 200 nm at different pressures, through one MgF₂ window, which has an cutoff at 115 nm. The spectra were recorded by Cruz-Diaz et al. 2013 under a hydrogen pressure of 0.6 mbar (blue dashed line) and 1.0 mbar (black continuous line). The expected spectrum of our lamp for 0.75 mbar (red continuous line) is the interpolation of these two curves.