15min:

RYAN L. THOM, ADYA P. MISHRA AND R. W. FIELD, Department of Chemistry and G. R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139.

We present here a new rotational analysis of the surface electron ejection by laser excited metastables (SEELEM) spectrum of acetylene in the energy region of the 3 ₃ vibrational level of the A ¹A_u excited electronic state of C₂H₂. Experimental conditions have allowed for the first time the assignment of rotational quantum numbers to the long-lived, largely triplet-character SEELEM eigenstates, after which the doorway-mediated coupling of the triplet manifold to the singlet level can be fitted to a spin-orbit effective Hamiltonian. The results of this model concerning the vibronic identities of the triplet states, the magnitude of the spin-orbit interaction, and relative singlet/triplet SEELEM detectivities, will be discussed.