Photoelectron spectroscopy of PbS−

The photoelectron spectrum of the gas phase diatomic anion, PbS− has been recorded with 2.540 eV photons. Transitions from the X2Π PbS− anion ground state to the X1Σ neutral PbS ground state are observed and assigned. The adiabatic electron affinity of PbS was determined to be 8461 cm−1 (1.049 eV). From this value and an energetic cycle, the dissociation energy of PbS− dissociating into the ground states of Pb and S− was found to be 55.4 kcal/mole (2.40 eV). From a Franck–Condon analysis of the spectrum, the anion’s bond length, vibrational frequency, and anharmonicity constant were determined to be re=2.390 Å, ωe=367 cm−1, ωeχe=2.2 cm−1, respectively.