|
The Excitation Temperature () is defined for a population of particles via the Boltzmann factor. It satisfies : where ''nu'' and ''nl'' represent the number of particles in an upper (''e.g.'' excited) and lower (''e.g.'' ground) state, and ''gu'' and ''gl'' their statistical weights respectively. Thus the excitation temperature is the temperature at which we would expect to find a system with this ratio of level populations. However it has no actual physical meaning except when in local thermodynamical equilibrium. The excitation temperature can even be negative for a system with inverted levels (such as a maser). In observations of the 21 cm line, the apparent value of the excitation temperature is often called the "spin temperature". ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「excitation temperature」の詳細全文を読む スポンサード リンク
|