Experimental determination of inelastic lifetimes of hot electrons
using low- loss EELS
C. Hébert, A. Satz, P. Schattschneider
Institute for Solid State Physics, Vienna University of Technology, Wiedner
Hauptstraße 8-10, A-1040 Wien, Austria.
Electron dynamics in solid materials play a key role in a variety of physical and
chemical phenomena. Low energy excited electrons (up to 10-20 eV) have a finite
lifetime which can be attributed to the e-e inelastic scattering. This lifetime can be
directly or indirectly observed in numerous analytical methods (e.g photoelectron
spectroscopy, direct and inverse photoemission spectroscopy but also in electron
energy loss near edge structure analysis).
The lifetime t of the excited electron is energy dependent and directly related to the
loss function e [1] :
The integral is done over all the kinematically possible values of q.
The loss function can be retrieved experimentally as a function of energy E=ħw for
different values of momentum transfer q by an angle resolved acquisition of the low
loss spectrum.
Left: low loss spectra of aluminum acquired for different values of the momentum
transfer q. Right: Lifetime broadening G= ħ /t obtained from the formula above
With this method we are able to retrieve the lifetime of hot electrons for various
materials without need of modeling the loss function.[2]
References
[1]
D Pines and P Nozières, The theory of quantum liquids, 1998.
[2]
The authors acknowledge the financial support of the Hochschuljubiläumsstiftung der Stadt Wien ( grant H-175/2001)