OBSERVATION OF THE P2 RADICAL BY RESONANCE-ENHANCED MULTIPHOTON IONIZATION SPECTROSCOPY

Three hitherto unobserved vibrational levels of the b'3SIGMA(u)- electronic state of P2 have been identified via the rotationally resolved, one-photon resonance enhancements they provide in the multiphoton ionisation spectrum of this radical. Analysis yields an extended set of spectroscopic constants for the b'3SIGMA(u)- state and a first estimate of the relative strengths of the parallel and perpendicular contributions to the P2(b'3SIGMA(u)--X1SIGMA(g)+) transition moment. One additional, particularly intense but unresolved feature observed at an excitation wavelength of ca. 320.75 nm is tentatively assigned in terms of a two-photon resonance involving a Rydberg State of P2 with 1SIGMA(g)+ symmetry.