Rotationally resolved pulsed-field ionization photoelectron bands for O-2(+)(A (2)Pi(u),v(+)=0-12) in the energy range of 17.0-18.2 eV

We have obtained rotationally resolved pulsed-field ionization photoelectro n (PFI-PE) spectra for O-2 in the energy range of 17.05-18.13 eV, covering the ionization transitions O-2(+)(A (2)Pi(u),v(+)=0-12,N+)<-- O-2(X (3)Sigm a(g)(-),v "=0,N "). Although these O-2(+)(A (2)Pi(u),v(+)) PFI-PE bands hav e significant overlaps with vibrational bands for O-2(+)(a (4)Pi(u)) and O- 2(+)(X (2)Pi(g)), we have identified all the O-2(+)(A (2)Pi(u),v(+)=0-12) b ands by simulation of spectra obtained using supersonically cooled O-2 samp les with rotational temperatures approximate to 20 and 220 K. While these v (+)=0-12 PFI-PE bands represent the first rotationally resolved photoelectr on data for O-2(+)(A (2)Pi(u)), the PFI-PE bands for O-2(+)(A (2)Pi(u),v(+) =9 and 10) are the first rotationally resolved spectroscopic data for these levels. The simulation also allows the determination of accurate ionizatio n energies, vibrational constants, and rotational constants for O-2(+)(A (2 )Pi(u),v(+)=0-12). The analysis of the PFI-PE spectra supports the conclusi on of the previous emission study that the O-2(+)(A (2)Pi(u),v(+)=9 and 10) states are strongly perturbed by a nearby electronic state. (C) 2000 Ameri can Institute of Physics. [S0021-9606(00)01703-7].