The notion of light quantization was first introduced by Planck. Its validity is based on solid experimental evidence, most notably the photoelectric effect. The basic physical process underlying this effect is the emission of electrons in metals exposed to light. No photoelectrons are emitted from the metal when the incident light is below a minimum frequency, regardless of its intensity.
For any particular material, there is a threshold frequency that must be exceeded, independent of light intensity, to observe any electron emission.
Three-step model[ edit ] In the X-ray regime, the photoelectric effect in crystalline material is often decomposed into three steps: The hole left behind can give rise to Auger effectwhich 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. Ballistic transport[ clarification needed ] 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.
Light, and especially ultra-violet light, discharges negatively electrified bodies with the production of rays of the same nature as cathode rays. Sunlight is not rich in ultra-violet rays, as these have been absorbed by the atmosphere, and it does not produce nearly so large an effect as the arc-light.
Many substances besides metals discharge negative electricity under the action of ultraviolet light: Schmidt  and O. InWilloughby Smith discovered photoconductivity in selenium while testing the metal for its high resistance properties in conjunction with his work involving submarine telegraph cables.
His receiver consisted of a coil with a spark gapwhere a spark would be seen upon detection of electromagnetic waves. He placed the apparatus in a darkened box to see the spark better.
However, he noticed that the maximum spark length was reduced when in the box. A glass panel placed between the source of electromagnetic waves and the receiver absorbed ultraviolet radiation that assisted the electrons in jumping across the gap.
When removed, the spark length would increase. He observed no decrease in spark length when he replaced the glass with quartz, as quartz does not absorb UV radiation. Hertz concluded his months of investigation and reported the results obtained.
He did not further pursue the investigation of this effect. The discovery by Hertz  in that the incidence of ultra-violet light on a spark gap facilitated the passage of the spark, led immediately to a series of investigations by Hallwachs Hoor,  Righi  and Stoletow        on the effect of light, and especially of ultra-violet light, on charged bodies.
It was proved by these investigations that a newly cleaned surface of zinc, if charged with negative electricity, rapidly loses this charge however small it may be when ultra-violet light falls upon the surface; while if the surface is uncharged to begin with, it acquires a positive charge when exposed to the light, the negative electrification going out into the gas by which the metal is surrounded; this positive electrification can be much increased by directing a strong airblast against the surface.
If however the zinc surface is positively electrified it suffers no loss of charge when exposed to the light: According to an important research by Wilhelm Hallwachsozone played an important part in the phenomenon.
It was at the time not even sure that the fatigue is absent in a vacuum. In the period from February and untila detailed analysis of photoeffect was performed by Aleksandr Stoletov with results published in 6 works;       four of them in Comptes Rendusone review in Physikalische Revue translated from Russianand the last work in Journal de Physique.
First, in these works Stoletov invented a new experimental setup which was more suitable for a quantitative analysis of photoeffect.
One of his other findings resulted from measurements of the dependence of the intensity of the electric photo current on the gas pressure, where he found the existence of an optimal gas pressure Pm corresponding to a maximum photocurrent ; this property was used for a creation of solar cells.
Thomson investigated ultraviolet light in Crookes tubes. In the research, Thomson enclosed a metal plate a cathode in a vacuum tube, and exposed it to high-frequency radiation. The amount of this current varied with the intensity and color of the radiation.
Larger radiation intensity or frequency would produce more current. As the effect was produced across several centimeters of air and made very great positive and small negative ions, it was natural to interpret the phenomenon, as did J. Thomson, as a Hertz effect upon the solid or liquid particles present in the gas.Oct 14, · In this video, I have discussed the experimental study of photoelectric effect.
Confirmation of Electromagnetic Waves - Duration: Physics4students 34, views. The photoelectric effect: experimental confirmation concerning a widespread misconception in the theory. Darren Wong 1, Paul Lee 1, Gao Shenghan 2, Wang Xuezhou 2, Huan Yan Qi 2 and Foong See Kit 1,3. The photoelectric effect is widely taught in schools and institutions.
The photoelectric effect is widely taught in schools and institutions. It is common knowledge that in order for photoelectrons to be emitted, the energy of the incoming photons must be greater than the work function of the irradiated metal (i.e.
hv greater than [phi][subscript emitter]). Its validity is based on solid experimental evidence, most notably the photoelectric effect. The basic physical process underlying this effect is the emission of electrons in metals exposed to light.
The basic physical process underlying this effect is the emission of electrons in metals exposed to light. This experiment investigates the photoelectric effect, which can be understood in terms of the particle nature of light. Much of the initial confirmation of the wave nature of electromagnetic radiation is attributed to experiments performed by Heinrich Hertz around Title The Photoelectric Effect – Experimental confirmation concerning a widespread Misconception in the Theory Gao Shenghan 1, Huan Yan Qi 1, Wang Xuezhou 1, Darren Wong 2, Paul Lee 2 and Foong See Kit 2 1 Raffles Institution, One Raffles Institution Lane, Singapore 2 Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore.