A double time-of-flight multi-electron-ion coincidence spectroscopy technique

by Prof. Raimund Feifel (Department of Physics and Astronomy, Uppsala University)

Thursday 21 Feb 2008, 10:00 → 11:00 Europe/Stockholm

The interpretation of the photoelectric effect by Albert Einstein in 1905 opened the way for photoelectron spectroscopy as pioneeringly developed in Uppsala. It reveals mainly the transitions to singly-ionised states of the system studied.

The absorption of a single photon may also lead to the ejection of two or more electrons from the same target species. If all the ejected electrons can be detected in coincidence and energy analysed, the energy levels of the multiply-ionised system can be obtained. This experiment is in effect photoelectron spectroscopy of multiply charged ions. Studies of dicationic states by this means are referred to as PhotoElectron-PhotoElectron COincidence (PEPECO) spectroscopy.

In this seminar the fundamental aspects of conventional photoelectron spectroscopy will be briefly recapitulated along with the presentation of a novel technique recently invented for multi-electron-ion coincidence spectroscopy. Examples of studies of single and double photoionisation of atoms and molecules will be given and mechanisms for multiple ionisation processes will be discussed as well as energy relationships.

Slides 80221_time_of_flight.ppt