Ground state rotational spectrum of nitrogen trifluoride: The KÂ =Â 3 splittings of 14NF3 and 15NF3

The ground state rotational spectrum of the 14NF3 and 15NF3 isotopic species of nitrogen fluoride has been observed in the ∼450-810 GHz frequency range. This investigation allowed us to improve the rotational parameters for both isotopologues. In particular, for the first time the K = 3 line splitting parameter and the sextic centrifugal distortion constants have been determined for 15NF3.