Angle Resolved Photoemission Spectroscopy


By measuring the kinetic energy (E) and momentum (k) of the electron in vacuum, the dispersion of the electron state E(k) in the solid can be determined


EF =            Fermi energy
Evac =         Vacuum level
Ei , ki=        initial energy and momentum of electron in solid
Ef , kf =      final energy and momentum of electron following excitation
E, k =         energy and momentum of free electron in vacuum after emission
Φ =             Evac – EF = work function
hν  =          incident photon energy

Energy conservation gives E(k) = hν – Φ – Ei(ki)

Momentum conservation parallel to the surface gives:


Momentum is not conserved perpendicular to the surface, but for a given inner potential V0, we can write: