Sneaking up on the Criegee intermediate from below: Predicted photoelectron spectrum of the CH2OO− anion and W3-F12 electron affinity of CH2OO

- The first ab initio calculation for the CH2OO− 'Criegee' anion are reported.
- The W3-F12 thermochemical protocol is applied to both anion and neutral CH2OO.
- An electron affinity is determined to be 0.567 eV for CH2OO.
- The predicted anion photoelectron spectrum involves two major progressions.