Not only is the effect of incomplete charge collection clearly visible in the immediate low-energy range of a peak in X-ray spectra, but also can usually extend over all energies below the affected peak, resulting in the so-called "background shelf". This is induced by continuum X-ray being inelastically scattered from the detector. The background shelf will increase the background from the peak energy down to zero energy and also result in more lower energy counts and fewer higher energy counts. The background shelf is usually obscured by the continuous x-ray background present in electron-excited spectra. This phenomenon can especially be significant with a strong peak. The problem is worst for X-ray peaks of higher energies, e.g. close to 20 keV.

Typically, the background shelf at one-half the energy of a parent peak has a relative intensity of ~0.1% of the peak. The total number of counts lost to the full peak is commonly ~1%, while poorly functioning detectors can have a 20% loss for peaks below a few keV, which can cause problems for both qualitative and quantitative analysis.