Electron affinity of the hafnium atom

Abstract

Hafnium is the last transition-metal element with an undetermined electron affinity. Using a slow-electron velocity-map imaging spectrometer equipped with a cold ion trap, the electron affinity of hafnium atoms is measured to be $1436(5)\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$ or 0.1780(6) eV. The cold ion trap employed in the present measurement is found to be crucial for reducing the background noise from the hafnium hydride anions.