Centrifugal distortion constants of pentafluorobenzene from its pure rotation spectrum

The centrifugal distortion analysis of the pure rotational spectrum of pentafluorobenzene in the frequency region of 8 to 18 GHz involvingJ upto 54 has yielded the following rotational and quartic centrifugal distortion constants: $$\begin{gathered} A'' = 1480 \cdot 8665 \pm 0 \cdot 0026 MHz, \tau = - 1 \cdot 751 \pm 0 \cdot 20 kHz, \hfill \\ B'' = 1030 \cdot 0782 \pm 0 \cdot 0025 MHz, \tau _2 = - 0 \cdot 567 \pm 0 \cdot 066 kHz, \hfill \\ C'' = 607 \cdot 5152 \pm 0 \cdot 0026 MHz, \tau _{aaaa} = - 0 \cdot 765 \pm 0 \cdot 068 kHz, \hfill \\ \tau _{bbbb} = - 0 \cdot 612 \pm 0 \cdot 065 kHz, \hfill \\ \tau _{cccc} = - 0 \cdot 547 \pm 0 \cdot 068 kHz. \hfill \\ \end{gathered} $$