Pulsed photodetachment microscopy and the electron affinity of iodine

Photodetachment microscopy is carried out on a beam of ¹²⁷I ^- ions with a nanosecond pulsed laser. The photoelectron interferograms are recorded by means of a digital camera that images the light spots produced by the amplified photoelectrons on a phosphor screen. This is the first implementation of such an optical imaging technique in photodetachment microscopy. Due to their sensitivity to the photoelectron energy, the recorded electron interferograms can be quantitatively analysed to produce a measure of the electron affinity of iodine ^eA(¹²⁷I) with an accuracy improved by more than a factor of 2 with respect to the best previous measurement. The result is 2467 287.4(29) m^-1 or 3.059 0463(38) eV.