OBSERVATION OF DIPOLE-BOUND STATE AND HIGH-RESOLUTION PHOTOELECTRON IMAGING OF COLD ACETATE ANIONS

We report the observation of a dipole-bound state and a high-resolution photoelectron imaging study of cryogenically cooled acetate anions (CH$_{3}$COO$^{-}$). Both high-resolution non-resonant and resonant photoelectron spectra via the dipole-bound state of CH$_{3}$COO$^{-}$ are obtained. The binding energy of the dipole-bound state relative to the detachment threshold is determined to be 53 $pm{8}$ wn. The electron affinity of the chem{CH_3COObullet} neutral radical is measured accurately as 26 236 $pm{8}$ wn (3.2528 $pm{ 0.0010}$ eV) using high-resolution photoelectron imaging. This accurate electron affinity is validated by observation of autodetachment from two vibrational levels of the dipole-bound state of CH$_{3}$COO$^{-}$. Excitation spectra to the dipole-bound states yield rotational profiles, allowing the rotational temperature of the trapped CH$_{3}$COO$^{-}$ anions to be evaluated $^{1}$. [1] D. L. Huang, G. Z. Zhu and L. S. Wang, $it{J. Chem. Phys.}$, 2015, $boldsymbol{142}$, 09110