Rotational temperature measurements in molecular plasmas using nonadditive Tsallis statistics

Tsallis' nonadditive statistics was employed to determine rotational temperatures in low-temperature nonequilibrium molecular plasmas. The First Negative and Second Positive Systems of nitrogen were used as test cases with classical two-Boltzmann distributions that may be replaced successfully by one Tsallis distribution. In our experimental conditions for First Negative System, only one Boltzmann distribution fails to account the intensities of rotational levels. An alternative approach to resolve this problem is to consider the rotational levels as a linear combination of two-Boltzmann equilibrium distributions. However this method requires three adjustable parameters; two rotational temperatures and a free parameter which describes the relative contribution of the hot and cold temperatures. Tsallis' temperature is close to the coldest one obtained by Boltzmann method and provides a consistent statistical interpretation. The nonadditive method could be, equally successfully, extended to other nitrogen systems and molecular plasmas.