Spectroscopic observation of Feshbach resonances in the tellurium dimer anion

Abstract

We report on the high-resolution photodetachment spectroscopy of the cryogenically cooled anionic tellurium dimer (Te2−). The high-resolution resonant photoelectron spectrum yields an accurate electron affinity of 16 689.7(92) cm−1 or 2.0693(11) eV for Te2. Two resonant states of Te2− anions have been identified, positioned at 1092(17) cm−1 below and 250(11) cm−1 above the photodetachment threshold, respectively. The spectra of resonant two-photon detachment (R2PD) and autodetachment from a specific vibrational level through a Feshbach resonance exhibit notable non-Franck–Condon behaviors. Using the spectroscopic data from the current experiment, the equilibrium bond distances and spectroscopic constants of the ground state and two electronically excited states of Te2− were determined.