15min:

KYLE L. BITTINGER, WILTON L. VIRGO AND ROBERT W. FIELD, Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.

Several bands of acetylene involving the near degenerate non-symmetric bending modes ₄ and ₆ of S₁ have been recorded by simultaneous laser induced fluorescence and gold surface electron ejection by laser-excited metastables (Au:SEELEM). The Au:SEELEM spectra indicate pronounced differences in coupling to long-lived states between the torsion ( ₄) and in-plane bend ( ₆). These results will be examined in light of the fact that ab initio calculations predict a nonplanar equilibrium geometry for the third triplet state, which mediates coupling between S₁ and the triplet manifold.