A supersonic beam of metastable He(*) atoms and He(2) (*) a (3)Sigma(u) (+) molecules has been generated using a pulsed discharge at the exit of a pulsed valve prior to the gas expansion into vacuum. Pulsed-field-ionization zero-kinetic-energy photoelectron spectra of the He(2) (+) X(+) (2)Sigma(u) (+) (v(+)=0-2)<--He(2) (*) a (3)Sigma(u) (+) (v(")=0-2) transitions and photoionization spectra of He(2) (*) in the vicinity of the lowest ionization thresholds have been recorded. The energy level structures of (4)He(2) (+) X(+) (2)Sigma(u) (+) (v(+)< or =2,N(+)< or =23) and (3)He(2) (+) X(+) (2)Sigma(u) (+) (v(+)=0,N(+)< or =11) have been determined, and an accurate set of molecular constants for all isotopomers of He(2) (+) has been derived in a global analysis of all spectroscopic data reported to date on the low vibrational levels of He(2) (+). The analysis of the photoionization spectrum by multichannel quantum defect theory has provided a set of parameters describing the threshold photoionization dynamics.

The rotationally resolved PFI-ZEKE (pulsed-field ionization zero-kinetic energy) photoelectron spectrum of ND 3 has been recorded at the v 2 + = 0, 1 and 2 thresholds, by single-photon VUV excitation from the ground-state. An assignment of the 2 2 A X     1 1 A X  spectrum is presented, allowing a determination of the adiabatic ionization potential of ND 3 (82261.7(15) cm-1) and of the rotational constants and positions of the v 2 + = 0, 1 and 2 vibrational levels of the ND 3 + ion. These parameters are used in a multichannel quantum defect theory (MQDT) simulation of the highresolution photoionization spectrum in the range 82100-83300 cm-1 [(R. Seiler et al., J. Chem. Phys. 118 10024 (2003)]. A good simulation and an assignment of around 80% of the lines of the ND 3 photoionization spectrum are achieved, verifying the validity of the molecular constants derived from the PFI-ZEKE photoelectron spectrum and also the quantum defect parameters derived from ab initio calculations.

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