Electron Emission Delay Is Clue To Dynamics

It takes about 20 attoseconds longer for a neon atom to emit an electron from its 2p orbital than from its 2s orbital after absorbing a photon, reports a group led by Martin Schultze, Vladislav S. Yakovlev, and Ferenc Krausz of Ludwig Maximilian University of Munich and Max Planck Institute of Quantum Optics, both in Germany (Science 2010, 328, 1658). The researchers observed the photoemission delay by using a type of pump-probe laser experiment known as attosecond streaking. The time difference is likely due to the transfer of energy to the outgoing electron from the remaining electrons as they adjust to new energy levels in the now positively charged neon ion. Now that researchers know the length of the delay—at least within 5 attoseconds—the number can be used to improve theoretical models of electron dynamics, the authors say. A better understanding of the phenomenon could also provide insight into the multielectron response of metals and semiconductors to sudden excitations.