High resolution photodetachment spectroscopy of negative ions via slow photoelectron imaging

A technique for high resolution anion photodetachment spectroscopy is presented that combines velocity map imaging and anion threshold photodetachment. This method, slow electron velocity-map imaging, provides spectral line widths of better than 1 meV. Spectra over a substantial range of electron kinetic energies are recorded in a single image, providing a dramatic reduction of data acquisition time compared to other techniques with comparable resolution. We apply this technique to atomic iodine and the van der Waals cluster I.CO2 as test systems, and then to the prereactive Cl.D2 complex where partially resolved structure assigned to hindered rotor motion is observed.