Population inversion | 農藥百科
![Population inversion](https://i.imgur.com/WMTbIbA.jpg)
Inscience,specificallystatisticalmechanics,apopulationinversionoccurswhileasystemexistsinastateinwhichmoremembersofthesystemarein ...
![Population inversion](https://i.imgur.com/WMTbIbA.jpg)
In physics, specifically statistical mechanics, a population inversion occurs while a system (such as a group of atoms or molecules) exists in a state in which more members of the system are in higher, excited states than in lower, unexcited energy states. It is called an "inversion" because in many familiar and commonly encountered physical systems, this is not possible. This concept is of fundamental importance in laser science because the production of a population inversion is a necessary step in the workings of a standard laser.
Boltzmann distributions and thermal equilibrium[edit]To understand the concept of a population inversion, it is necessary to understand some thermodynamics and the way that light interacts with matter. To do so, it is useful to consider a very simple assembly of atoms forming a laser medium.
Assume there is a group of N atoms, each of whic...