Highly accurate H-2 Lyman and Werner band laboratory measurements and an improved constraint on a cosmological variation of the proton-to-electron mass ratio

The spectral lines of Lyman and Werner band transitions were investigated with the use of a tunable narrow band extreme ultraviolet (XUV) laser source. The data was recorded by performing 1 extreme ultraviolet (XUV) + 1 UV resonance-enhanced photoionization under nearly Doppler-free conditions in a molecular beam. The data was used to compare the spectral lines observed at high redshift in three quasars, which had produced the lines 12 billion years ago. The data set was also found to be useful for calculating wavelengths for additional nonmeasured lines via the known ground-state rotational splittings.