Question: What does the energy of the emitted electrons depend on?
About the article "Photoelectric effect", section "Emission mechanism".

Candidate passages:
Emitted colors depend on the electronic configuration of the elements involved.
Heat energy from the flame excites electrons to a higher quantum level, and the atoms emit characteristic colors (photons with energies corresponding to the visible spectrum) as they return to lower energy levels. 
The photons of a light beam have a characteristic energy proportional to the frequency of the light.
In the photoemission process, if an electron within some material absorbs the energy of one photon and acquires more energy than the work function (the electron binding energy) of the material, it is ejected.
If the photon energy is too low, the electron is unable to escape the material.
Since an increase in the intensity of low-frequency light will only increase the number of low-energy photons sent over a given interval of time, this change in intensity will not create any single photon with enough energy to dislodge an electron.
Thus, the energy of the emitted electrons does not depend on the intensity of the incoming light, but only on the energy (equivalently frequency) of the individual photons.
It is an interaction between the incident photon and the outermost electrons.
Electrons can absorb energy from photons when irradiated, but they usually follow an "all or nothing" principle.
All of the energy from one photon must be absorbed and used to liberate one electron from atomic binding, or else the energy is re-emitted.
If the photon energy is absorbed, some of the energy liberates the electron from the atom, and the rest contributes to the electron's kinetic energy as a free particle.
The elastic backscattering of low energy electrons from surfaces is strong.
The reflectivity coefficients of surfaces depend strongly on the energy of incident electrons and the nuclear charge, in a non-monotonic fashion.
Therefore, contrast can be maximized by varying the energy of the electrons incident at the surface. 
The potential energy of an electron in an atom is negative, its dependence of its position reaches the minimum (the most absolute value) inside the nucleus, and vanishes when the distance from the nucleus goes to infinity, roughly in an inverse proportion to the distance.
In the quantum-mechanical model, a bound electron can only occupy a set of states centered on the nucleus, and each state corresponds to a specific energy level; see time-independent Schrödinger equation for theoretical explanation.
An energy level can be measured by the amount of energy needed to unbind the electron from the atom, and is usually given in units of electronvolts (eV).
The lowest energy state of a bound electron is called the ground state, i.e.
stationary state, while an electron transition to a higher level results in an excited state.
The electron's energy raises when "n" increases because the (average) distance to the nucleus increases.
Dependence of the energy on azimuthal quantum number is caused not by electrostatic potential of the nucleus, but by interaction between electrons.
For an electron to transition between two different states, e.g.
grounded state to first excited level (ionization), it must absorb or emit a photon at an energy matching the difference in the potential energy of those levels, according to Niels Bohr model, what can be precisely calculated by the Schrödinger equation.
Electrons jump between orbitals in a particle-like fashion.
For example, if a single photon strikes the electrons, only a single electron changes states in response to the photon; see Electron properties.
The energy of an emitted photon is proportional to its frequency, so these specific energy levels appear as distinct bands in the electromagnetic spectrum.
Each element has a characteristic spectrum that can depend on the nuclear charge, subshells filled by electrons, the electromagnetic interactions between the electrons and other factors.
When a continuous spectrum of energy is passed through a gas or plasma, some of the photons are absorbed by atoms, causing electrons to change their energy level.
Those excited electrons that remain bound to their atom spontaneously emit this energy as a photon, traveling in a random direction, and so drop back to lower energy levels.
Thus the atoms behave like a filter that forms a series of dark absorption bands in the energy output.
(An observer viewing the atoms from a view that does not include the continuous spectrum in the background, instead sees a series of emission lines from the photons emitted by the atoms.)
Spectroscopic measurements of the strength and width of atomic spectral lines allow the composition and physical properties of a substance to be determined.
Close examination of the spectral lines reveals that some display a fine structure splitting.
This occurs because of spin–orbit coupling, which is an interaction between the spin and motion of the outermost electron.
When an atom is in an external magnetic field, spectral lines become split into three or more components; a phenomenon called the Zeeman effect.
This is caused by the interaction of the magnetic field with the magnetic moment of the atom and its electrons.
Some atoms can have multiple electron configurations with the same energy level, which thus appear as a single spectral line.
The interaction of the magnetic field with the atom shifts these electron configurations to slightly different energy levels, resulting in multiple spectral lines.
The presence of an external electric field can cause a comparable splitting and shifting of spectral lines by modifying the electron energy levels, a phenomenon called the Stark effect.
If a bound electron is in an excited state, an interacting photon with the proper energy can cause stimulated emission of a photon with a matching energy level.
For this to occur, the electron must drop to a lower energy state that has an energy difference matching the energy of the interacting photon.
The emitted photon and the interacting photon then move off in parallel and with matching phases.
That is, the wave patterns of the two photons are synchronized.
This physical property is used to make lasers, which can emit a coherent beam of light energy in a narrow frequency band. 
The light emitted by a spark does not come from the current of electrons itself, but from the material medium fluorescing in response to collisions from the electrons.
When electrons collide with molecules of air in the gap, they excite their orbital electrons to higher energy levels.
When these excited electrons fall back to their original energy levels, they emit energy as light.
It is impossible for a visible spark to form in a vacuum.
Without intervening matter capable of electromagnetic transitions, the spark will be invisible (see vacuum arc).