ROLE OF ELECTRON-SPIN COUPLING IN MOLECULAR PHOTOIONIZATION - THE B(4)SIGMA(-)(G)[-X(3)SIGMA(-)(G) PHOTOELECTRONIC TRANSITION OF O-2

The electron spin splittings of the rotational levels of the b and X s tates have been resolved in the pulsed-field-ionization zero-kinetic-e nergy photoelectron spectrum of the O(2)(+)b (4)Sigma(g)(-) <-- O2X (3 )Sigma(g)(-) transition. Photoionization leads to a very selective pop ulation of specific spin components of ionic rotational levels. Of the nine b (4)Sigma(g)(-) (v(+) = 0, N+ = 1, F-j, j = 1,2,3) <-- X (3)Sig ma(g)(-) (v'' = 0, N'' = 1, F-i, i = 1,2,3) components that constitute the N+ = 1 <-- N'' = 1 rotational transition, only those with i = j a re observed with significant intensity. The results demonstrate the im portance of a detailed consideration of the electron spin for a satisf actory description of molecular photoionization.