			15min:

GATEWAY MEDIATED INTERSYSTEM CROSSING IN C₂H₂.

KEVIN L. CUNNINGHAM, STEPHEN DRUCKER, SELEN ALTUNATA, CHRISTOPHER G. MORGAN AND ROBERT W. FIELD, Department of Chemistry, Massachusetts Institute of Technology, Cambridge MA 02139-4307.

Recent Surface Electron Ejection by Laser-Excited Metastable (SEELEM) spectra have provided a clearer picture of the intersystem crossing of the 3₃ level of the S₁ surface of C₂H₂ to near-degenerate triplet states. The simultaneously recorded LIF and SEELEM spectra indicate that a single vibrational level of the T₃ surface couples the 3₃ level of the S₁ surface to a dense manifold of T₁ and T₂ states. This proposed coupling mechanism, Gateway Mediated Intersystem Crossing (GMISC), and other proposals will be discussed in light of the new data.