What do you mean by threshold frequency?

As a domain expert in physics, particularly in the field of atomic and quantum physics, I can explain the concept of the threshold frequency. The threshold frequency is a specific frequency of incident electromagnetic radiation, such as light, that is required to overcome the binding forces holding electrons in atoms or molecules. When the frequency of the incoming radiation is below this threshold, the electrons will not gain enough energy to escape from the atom or molecule. However, when the frequency exceeds the threshold frequency, the electrons can gain enough energy to be ejected, a process known as photoelectric emission. In the context of the photoelectric effect, which was explained by Albert Einstein and for which he received the Nobel Prize in Physics in 1921, the threshold frequency is directly related to the work function of the material. The work function is the minimum energy required to remove an electron from the surface of a material. The energy of the incident photons must be greater than or equal to the work function for electrons to be emitted. Here's the explanation in English, followed by the translation in Chinese, separated by "

Threshold frequency is defined as the minimum frequency of incident light which can cause photo electric emission i.e. this frequency is just able to eject electrons with out giving them additional energy. It is denoted by . WORK FUNCTION.