Observation of molecular hyperfine structure in the extreme ultraviolet: The HF C-X spectrum

Clearly resolved hyperfine structure has been observed in the extreme ultraviolet (XUV) spectra of the C Π1, v=0-X 1 +, v=0 transition of H F 19 obtained through 1 XUV+1 UV resonance enhanced multiphoton ionization spectroscopy. The hyperfine splitting within the R -branch lines shows significant perturbations, which we attribute to mixing with the rotational levels of the nearby v=29 level of the B 1 + ion-pair state. A deperturbation analysis quantitatively explains the apparent variation of the fluorine magnetic hyperfine parameter aF, for which a value of 4034(83) MHz was obtained by averaging over the values derived from the R (0) -R (4) lines, after correcting for the effects of the perturbations. © 2008 American Institute of Physics.