Knowledge Bank

In the two color ZEKE-PFI $studya$ of the $CdCH3$ radical well-resolved K rotational structure has been observed in some vibronic states. We have extended the previous theoretical formulation of the selection $rulesb$ 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 H""{o}nl-London-type line strength factor S for the ionizing $e-e$ vibronic transition can be written as $S(N+K+p+;NKp)=\delta p+,-p(2N++1)(2N+1)\sum lA,\lambda A=1,-2,A,-5,\dots alA\lambda A2AtANN+(N+lAN-K+-\lambda A-K)2,$ where p denotes the state's parity and the $AlANN+$ are determined by the wavepacket composition of the Rydberg state that is subsequently field ionized. The $alA\lambda A$ are coefficients in an expansion of the neutral state's vibronic wavefunction $|\varphi ⟩$ in terms of a core wavefunction $|\varphi cor⟩$, its vibrational wavefunctions $|\varphi vlb⟩$, and its single electron atomic wavefunctions $|lA,\lambda A⟩$: $|\varphi ⟩=|\varphi cor⟩\sum lA,\lambda AalA\lambda A|\varphi vib⟩|lA,\lambda A⟩$