Question: Why does the quantity of electrons change as an aftereffect of photoelectric outflow?
About the article "Photoelectric effect", section "Experimental observations of photoelectric emission".

Candidate passages:
In the X-ray regime, the photoelectric effect in crystalline material is often decomposed into three steps:  Inner photoelectric effect (see photodiode below).
The hole left behind can give rise to auger effect, which is visible even when the electron does not leave the material.
In molecular solids phonons are excited in this step and may be visible as lines in the final electron energy.
The inner photoeffect has to be dipole allowed.
The transition rules for atoms translate via the tight-binding model onto the crystal.
They are similar in geometry to plasma oscillations in that they have to be transversal.
Ballistic transport of half of the electrons to the surface.
Some electrons are scattered.
Electrons escape from the material at the surface.
In the three-step model, an electron can take multiple paths through these three steps.
All paths can interfere in the sense of the path integral formulation.
For surface states and molecules the three-step model does still make some sense as even most atoms have multiple electrons which can scatter the one electron leaving. 
Combining two scientific discoveries.
The invention of the photomultiplier is predicated upon two prior achievements, the discoveries of the photoelectric effect and secondary emission (i.e., the ability of electrons in a vacuum tube to cause the emission of additional electrons by striking an electrode). 
Apker followed up his work on the photoelectric effect with an investigation of the photoelectric properties of the alkali halides, particularly potassium iodide.
In potassium iodide, an ionic crystal, some iodide ions can be removed and their vacant places will be filled by electrons.
Called "F-Centers," these defects absorb visible and ultraviolet light, coloring the crystals at photon energies where they are usually transparent.
Additionally, the absorption of visible radiation can free trapped electrons inside the crystal and produce photoconductivity.
Apker found that in addition to visible radiation, near-ultraviolet radiation also produces photoconductitivty.
Deeper into the ultraviolet spectrum, however, potassium iodide has a strong absorption line due to the formation of chargeless particles called excitons.
These excitons transfer energy to the electrons in the F-Centers with remarkably high efficiency, and these excited electrons are excited from the crystals in exciton-induced photoemission.
Apker observed the same sort of behavior in other crystals such as barium oxide. 
This internal conversion process is also not to be confused with the similar photoelectric effect, which also may occur with electron emissions associated with gamma radiation, in which an incident gamma photon emitted from a nucleus interacts with an electron, expelling the electron from the atom.
Thus, gamma photoelectric-effect electron emission may "also" cause high-speed electrons to be emitted from radioactive atoms without beta decay.
However, in internal conversion, the nucleus does not first emit an intermediate real gamma ray, and therefore need not change angular momentum or electric moment.
Also, electrons from the gamma photoelectric effect show a spread in energy, depending on how much energy has been imparted to the ejected electron by the gamma ray that interacts with it—an amount that is variable depending on the angle of gamma photon scattering from the electron.
Further, a gamma ray is still emitted in photoelectric processes, but one that possesses a fraction of the energy compared to the gamma ray that left the nucleus.
By contrast, in internal conversion, no gamma ray is emitted at all, and the electron energy is fixed at a single, typical value.
Auger electrons, which may also be produced after an internal conversion, arise from a mechanism that is different from that of internal conversion, but is analogous to it.
Internal conversion electrons arise when an intense electric dipole field inside the nucleus accelerates an electron that has penetrated the nucleus and removes it from the atom.
Auger electrons similarly arise when an electric field is produced within an atom's electron cloud due to loss of another electron, and this field again induces the acceleration and removal of yet another of the atom's atomic orbital electrons.
Like IC electrons, Auger electrons also emerge in a sharp energy peak.
The electron capture process also involves an inner shell electron, which in this case is retained in the nucleus (changing the atomic number) and leaving the atom (not the nucleus) in an excited state.
The atom can relax by X-ray emission and/or by Auger electron emission.
Unstable nuclei can usually decay through both internal conversion and electron capture processes. 
The photoelectric effect will cause spacecraft exposed to sunlight to develop a positive charge.
This can be a major problem, as other parts of the spacecraft in shadow develop a negative charge from nearby plasma, and the imbalance can discharge through delicate electrical components.
The static charge created by the photoelectric effect is self-limiting, though, because a more highly charged object gives up its electrons less easily.