THEORETICAL INVESTIGATIONS OF THE ELECTRONIC-SPECTRA OF ZNCH3 - ANALYSIS OF SPIN-ORBIT-COUPLING AND JAHN-TELLER EFFECT

Ab initio calculations have been performed on the ground state and fir st excited states of ZnCH3 which correlates with Zn(4s4p, P-1 and P-3) +CH3 in its ground state, including the determination of the vibration al frequencies in the excited states. The calculation of the spin-orbi t contributions shows that the splitting of the E(1/2) and E(3/2) comp onents of the first excited state is large enough to eliminate the Jah n-Teller distortion. The potential curves corresponding to the Zn-C di stance present two important features. Firstly, the second excited sta te (B (2)A(1)) is repulsive in the ground state equilibrium geometry b ut is bounded at large distance (2.6 Angstrom) and more stable in this region than the first excited (A (2)E) state. The potential identific ation of two unexplained bands in the emission spectrum to the B--> X transition is discussed. Secondly, when the spin-orbit contribution is taken into account the j = 1/2 component of the first excited state e xhibits a two-well structure with a barrier of about 1000 cm-(1).