Synchrotron vacuum ultraviolet radiation studies of the D(1)Pi(u) state of H(2)

The 3pπD Π1u state of the H2 molecule was reinvestigated with different techniques at two synchrotron installations. The Fourier transform spectrometer in the vacuum ultraviolet wavelength range of the DESIRS beamline at the SOLEIL synchrotron was used for recording absorption spectra of the D Π1u state at high resolution and high absolute accuracy, limited only by the Doppler contribution at 100 K. From these measurements, line positions were extracted, in particular, for the narrow resonances involving Π1u− states, with an accuracy estimated at 0.06 cm−1. The new data also closely match multichannel quantum defect calculations performed for the Π− components observed via the narrow Q-lines. The Λ-doubling in the D Π1u state was determined up to v=17. The 10 m normal incidence scanning monochromator at the beamline U125/2 of the BESSY II synchrotron, combined with a home-built target chamber and equipped with a variety of detectors, was used to unravel information on ionization, dissociation, and intramo...