The rotational temperature is commonly used in thermodynamics, to simplify certain equations. It has units of temperature and is defined as
Where is the rotational constant, and k is the Boltzmann constant, given in wavenumbers per kelvin (the value of this is ~ 0.695 cm−1/K).
The rotational temperature is used commonly when finding the rotational partition function. There is much more relating to these quantities in rotational spectroscopy and the article regarding the rotational constant.