The VUV absorption spectrum of PbO vapor down to 300 Angstrom has been obse
rved for the first time. Four ionization energies have been determined from
Rydberg series at 8.73, 8.83, 12.81, and 26.28 eV corresponding to the (XI
I)-I-2, A(2)Sigma(+), (BX+)-X-2, and C(2)Sigma(+) electronic states of the
PbO+ ion. (C) 2000 Academic Press.