Electron Photodetachment Spectroscopy

Electron photodetachment spectroscopy reveals the excited electronic and vibrational states of gas-phase anions. These states serve as a molecular fingerprint, enabling the identification of unknown compounds. In comparison with other spectroscopic techniques, electron photodetachment spectroscopy provides complimentary information regarding the photophysical properties of the anion, and helps to further our understanding of these interesting systems.

Acquiring an electron photodetachment spectrum is relatively straight forward, and is illustrated above. First the anion of interest is isolated in a mass spectrometer. Then the ion is irradiated with a laser pulse. If the energy of the light matches a spectroscopic transition of the anion, electrons will be removed from some of the trapped anions. As the mass spectrometer is unable to see neutral molecules, electron detachment results in a decrease in ion signal. By monitoring the signal intensity from the mass spectrometer as a function of laser wavelength, we can generate an anion photo-detachment spectrum and reveal the electronic behavior of the ion.