The hyperfine spectrum of KF

A molecular beam electric resonance spectrometer was used to observe the hyperfine spectrum of KF, including both K isotopes, vibrational states 0–7 and rotational states 1–3. The 73 observed transitions were fitted with 14 parameters expressing the vibrational and rotational dependence of each of the molecular hyperfine constants. Experimental uncertainties of the order of 1 Hz were achieved.