Rotationally resolved vacuum ultraviolet pulsed field ionization-photoelectron vibrational bands for HD+(X 2Σg+,v+=0-20)

The authors have obtained rotationally resolved vacuum ultraviolet pulsed field ionization-photoelectron (vuv-PFI-PE) spectrum of HD in the photon energy range of 15.29-18.11 eV, covering the ionization transitions HD+(X (2)Sigma(+)(g),nu(+)=0-21,N+)<- HD(X (1)Sigma(+)(g),nu ''=0,J ''). The assignment of rotational transitions resolved in the vuv-PFI-PE vibrational bands for HD+(X (2)Sigma(+)(g),nu(+)=0-20) and their simulation using the Buckingham-Orr-Sichel (BOS) model are presented. Rotational branches corresponding to the Delta N=N+-J ''=0, +/- 1, +/- 2, +/- 3, and +/- 4 transitions are observed in the vuv-PFI-PE spectrum of HD. The BOS simulation shows that the perturbation of vuv-PFI-PE rotational line intensities due to near resonance autoionization is very minor at v(+)>= 5 and decreases as v(+) is increased. Thus, the rotationally resolved PFI-PE bands for HD+(nu(+)>= 5) presented here provide reliable estimates of state-to-state cross sections for direct photoionization of HD, while the rotationally resolved PFI-PE bands for HD+(v(+)< 5) are useful data for fundamental understanding of the near resonance autoionizing mechanism. On the basis of the rovibrational assignment of the vuv-PFI-PE bands, the ionization energies for the formation of HD+(X (2)Sigma(+)(g),nu(+)=0-20,N+) from HD(X (1)Sigma(+)(g),nu ''=0,J '') and the vibrational constants (omega(e), omega(e)chi(e), omega(e)y(e), and omega(e)z(e)), the rotational constants (B-e and alpha(e)), the vibrational energy spacings, and the dissociation energy for HD+(X (2)Sigma(+)(g)) are determined. As expected, these values are found to be in excellent agreement with high level theoretical predictions. (c) 2007 American Institute of Physics.