Knowledge Bank

The $X~2A1(0,0,0)$ ground vibronic state of $CH2+$ has been studied by pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectroscopy by recording transitions from the $X~\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}B1(0,0,0)$ ground vibronic state of $CH2$ which has been produced by photolysis of $CH2CO$ at 351 nm. The rotational energy level structure and the spin-rotation splittings of levels with $Ka\ge 1$ could be resolved. The rotational structure in the $X~\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}A1(0,0,0)$ state deviates strongly from that of a rigid rotor. The adiabatic ionization potential of $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}CH2$ has been determined to be $(83772\pm 3)cm-1$. Analysis of the photoionization selection rules indicates that the photoelectron is ejected as a superposition of $\ell$ even and $\ell$ odd partial waves.