Thanks for the reply, however I'm still confused.
As far as i understand: in this case of photoelectric absorption, Φ is not the work function but the binding energy, eg. for Si it has values over 100 eV.
I'm especially interested in detection of low energy photons (250-400 eV).
Example...
As far as i understand, this is the principle of solid state x-ray detectors:
1. A photon of energy E enters the detector and goes through photoelectric absorption
2. As a result a photoelectron with energy (E - Φ) is ejected, where Φ is the binding energy required to eject the photoelectron...