15min:

SERGEY I. PANOV, Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139; AND TERRY A. MILLER, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, Columbus, OH 43210.

In the two color ZEKE-PFI study of the \mathrmCdCH₃ radical well-resolved K rotational structure has been observed in some vibronic states. We have extended the previous theoretical formulation of the selection rules to cover the observed transitions. An important result is that the selection rules are determined by the vibronic structure of the intermediate state of the neutral from which the ionizing ZEKE transition occurs. For example, the Hönl-London-type line strength factor S for the ionizing e-e vibronic transition can be written as

\begineqnarray S\left(N⁺K⁺p⁺;NKp\right) = _p⁺,-p (2N⁺+1)(2N+1)\!\!\!\!\!\!\!\!\! \sum_l_A,\,\lambda_A=1,-2,4,-5,... \!\!\!\!\!\!\!\!\!a_l_A\lambda_A²\,A_l_ANN⁺ \left( \beginarrayccc N⁺ & l_A & N
-\!K⁺ & -\lambda _A & -\!K \endarray \right) ², \nonumber \endeqnarray

where p denotes the state's parity and the A_l_ANN⁺ are determined by the wavepacket composition of the Rydberg state that is subsequently field ionized. The a_l_A\lambda_A are coefficients in an expansion of the neutral state's vibronic wavefunction \left|\right> in terms of a core wavefunction \left|_cor\right>, its vibrational wavefunctions \left|_vib\right>, and its single electron atomic wavefunctions \left|l_A,\lambda_A\right>:

\begineqnarray \left|\right> =\left|_cor\right>\sum_l_A, \lambda_Aa_l_A\lambda_A \left| _vib\right> \left| l_A,\lambda _A\right> \nonumber \endeqnarray