A combined zero electronic kinetic energy spectroscopy and ion-pair dissociation imaging study of the $F2+(XΠg2)$ structure

Rotationally resolved pulsed field ionization and zero electronic kinetic energy photoelectron spectra for the transition $F2+(XΠg2)←F2(XΣg+1)$ have been recorded using the extreme ultraviolet coherence radiation. The vibrational energy spacings, rotational constants, and spin orbit coupling constants for the first three vibrational states of $F2+(XΠg2)$ have been determined accurately. The first adiabatic ionization potential (IP) of $F2$ is determined as $IP(F2)=126 585.7±0.5cm−1$⁠. To determine the threshold $Etipp$ for ion-pair production of $F2$⁠, the images of $F−(S01)$ in the velocity mapping conditions have also been recorded at the photon energy of $126 751cm−1$⁠. Taking the Stark effect into account, the $Etipp$ is determined as $Etipp(F2)=126 045±8cm−1$ $(15.628±0.001eV)$⁠. By combing the $IP(F2)$ and the $Etipp(F2)$ determined in this work and together with the reported ionization potential and electronic affinity of the $F$ atom, the bond dissociation energies of $F2$ and $F2+$ are determined as $D0(F2)=1.606±0.001eV$ and $D0(F2+)=3.334±0.001eV$⁠, respectively.