High resolution laser spectroscopy beyond 18 eV:: the B2Σu+←X1Σg+ photoelectronic transition of N2

Coherent, narrow-bandwidth laser radiation has been generated beyond 18 eV. The radiation has been used to record a rotationally resolved pulsed-field-ionization zero-kinetic-energy photoelectron spectrum of the B (2) Sigma(u)(+) <-- X (1) Sigma(g)(+) transition of N-2. Analysis of the rotational structure indicates that the removal of one of the two 2 sigma(u)* inner-valence-shell electrons is accompanied by substantial changes in the core rotational angular momentum quantum number: Rotational branches are observed with Delta N = N+ - N = +/- 1 and +/- 3, where N+ and N represent the core rotational angular momentum of the ion and the neutral, respectively. These branches can be explained by the ejection of a photoelectron with dominant iota = 0 and iota = 2 character. (C) 1998 Elsevier Science B.V.