In
physicsPhysics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
, the
Dember effect is when the
electronThe electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
current flowing from a
cathodeA cathode is an electrode through which electric current flows out of a polarized electrical device. Mnemonic: CCD .Cathode polarity is not always negative...
subjected to both illumination and a simultaneous electron bombardment is greater than the sum of the photoelectric current
and the secondary emission current
.
Discovered by Harry L. Dember (1882-1943) in 1925, this effect is due to the sum of the excitations of an electron by two means: photonic illumination and electron bombardment (i.e.the sum of the two excitations extracts the electron). In Dember’s initial study, he referred only to metals; however more complex materials have been analyzed since then.
The
photoelectric effectIn the photoelectric effect, electrons are emitted from matter as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light. Electrons emitted in this manner may be referred to as photoelectrons...
due to the illumination of the metallic surface extracts electrons (if the energy of the photon is greater than the extraction work) and excites the electrons which the photons haven’t got the energy to extract.
In a similar process, the electron bombardment of the metal both extracts and excites electrons inside the metal.
If we consider
a constant and increase
it can be observed that
has a maximum of about 150 times
.
On the other hand, considering I_2 a constant and we increase the intensity of the illumination
the
, supplementary current, tends to saturate. This is due to the usage in the photoelectric effect of all the electrons excited (sufficiently) by the primary electrons of
.
The Dember effect has no relation to the financial markets "December effect". See
January effectThe January effect is a calendar-related anomaly in the financial market where financial security prices increase in the month of January. This creates an opportunity for investors to buy stock for lower prices before January and sell them after their value increases.Therefore, the main...